Revert "Client-side protocol V2 support for fetching"

This reverts commit f802f06e7fd5a98f256b7b7727598491f563bf2f.

I had misunderstood how protocol V2 works. This implementation only
works if the negotiation during fetch is done in one round.

Fixing this is substantial work in BasePackFetchConnection. Basically
I think I'd have to change back negotiate to the V0 version, and have
a doFetch() that does

  if protocol V2
    doFetchV2()
  else
    doFetchV0()

with doFetchV0 the old code, and doFetchV2 completely new.

Plus there would need to be a HTTP test case requiring several
negotiation rounds.

This is a couple of days work at least, and I don't know when I will
have the time to revisit this. So although the rest of the code is
fine I prefer to back this out completely and not leave a only half
working implementation in the code for an indeterminate time.

Bug: 553083
Change-Id: Icbbbb09882b3b83f9897deac4a06d5f8dc99d84e
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

16 files changed, 125 insertions, 915 deletions

diff --git a/org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties b/org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties
index 3027e39a75..c9e48a5c09 100644
--- a/org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties
+++ b/org.eclipse.jgit/resources/org/eclipse/jgit/internal/JGitText.properties
@@ -232,7 +232,6 @@ downloadCancelled=Download cancelled
 downloadCancelledDuringIndexing=Download cancelled during indexing
 duplicateAdvertisementsOf=duplicate advertisements of {0}
 duplicateRef=Duplicate ref: {0}
-duplicateRefAttribute=Duplicate ref attribute: {0}
 duplicateRemoteRefUpdateIsIllegal=Duplicate remote ref update is illegal. Affected remote name: {0}
 duplicateStagesNotAllowed=Duplicate stages not allowed
 eitherGitDirOrWorkTreeRequired=One of setGitDir or setWorkTree must be called.
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/LsRemoteCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/LsRemoteCommand.java
index 77ecf3b367..a4ca309095 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/LsRemoteCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/LsRemoteCommand.java
@@ -164,7 +164,7 @@ public class LsRemoteCommand extends
 				refSpecs.add(new RefSpec("refs/heads/*:refs/remotes/origin/*")); //$NON-NLS-1$
 			Collection<Ref> refs;
 			Map<String, Ref> refmap = new HashMap<>();
-			try (FetchConnection fc = transport.openFetch(refSpecs)) {
+			try (FetchConnection fc = transport.openFetch()) {
 				refs = fc.getRefs();
 				if (refSpecs.isEmpty())
 					for (Ref r : refs)
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java
index 9887ed8230..b761210e63 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/JGitText.java
@@ -260,7 +260,6 @@ public class JGitText extends TranslationBundle {
 	/***/ public String downloadCancelledDuringIndexing;
 	/***/ public String duplicateAdvertisementsOf;
 	/***/ public String duplicateRef;
-	/***/ public String duplicateRefAttribute;
 	/***/ public String duplicateRemoteRefUpdateIsIllegal;
 	/***/ public String duplicateStagesNotAllowed;
 	/***/ public String eitherGitDirOrWorkTreeRequired;
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/BasePackConnection.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/BasePackConnection.java
index c9c6c0c25d..1417faee80 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/BasePackConnection.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/BasePackConnection.java
@@ -13,12 +13,7 @@
 
 package org.eclipse.jgit.transport;
 
-import static org.eclipse.jgit.transport.GitProtocolConstants.COMMAND_LS_REFS;
 import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_AGENT;
-import static org.eclipse.jgit.transport.GitProtocolConstants.REF_ATTR_PEELED;
-import static org.eclipse.jgit.transport.GitProtocolConstants.REF_ATTR_SYMREF_TARGET;
-import static org.eclipse.jgit.transport.GitProtocolConstants.VERSION_1;
-import static org.eclipse.jgit.transport.GitProtocolConstants.VERSION_2;
 
 import java.io.EOFException;
 import java.io.IOException;
@@ -26,28 +21,20 @@ import java.io.InputStream;
 import java.io.OutputStream;
 import java.text.MessageFormat;
 import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.HashMap;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
-import java.util.Map;
-import java.util.Objects;
 import java.util.Set;
 
-import org.eclipse.jgit.annotations.NonNull;
 import org.eclipse.jgit.errors.InvalidObjectIdException;
 import org.eclipse.jgit.errors.NoRemoteRepositoryException;
 import org.eclipse.jgit.errors.PackProtocolException;
 import org.eclipse.jgit.errors.RemoteRepositoryException;
 import org.eclipse.jgit.errors.TransportException;
 import org.eclipse.jgit.internal.JGitText;
-import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectIdRef;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.Repository;
-import org.eclipse.jgit.util.TemporaryBuffer;
 import org.eclipse.jgit.util.io.InterruptTimer;
 import org.eclipse.jgit.util.io.TimeoutInputStream;
 import org.eclipse.jgit.util.io.TimeoutOutputStream;
@@ -99,27 +86,17 @@ abstract class BasePackConnection extends BaseConnection {
 	protected boolean statelessRPC;
 
 	/** Capability tokens advertised by the remote side. */
-	private final Map<String, String> remoteCapabilities = new HashMap<>();
+	private final Set<String> remoteCapablities = new HashSet<>();
 
 	/** Extra objects the remote has, but which aren't offered as refs. */
 	protected final Set<ObjectId> additionalHaves = new HashSet<>();
 
-	private TransferConfig.ProtocolVersion protocol = TransferConfig.ProtocolVersion.V0;
-
 	BasePackConnection(PackTransport packTransport) {
 		transport = (Transport) packTransport;
 		local = transport.local;
 		uri = transport.uri;
 	}
 
-	TransferConfig.ProtocolVersion getProtocolVersion() {
-		return protocol;
-	}
-
-	void setProtocolVersion(@NonNull TransferConfig.ProtocolVersion protocol) {
-		this.protocol = protocol;
-	}
-
 	/**
 	 * Configure this connection with the directional pipes.
 	 *
@@ -164,15 +141,12 @@ abstract class BasePackConnection extends BaseConnection {
 	 * {@link #close()} and the exception is wrapped (if necessary) and thrown
 	 * as a {@link org.eclipse.jgit.errors.TransportException}.
 	 *
-	 * @return {@code true} if the refs were read; {@code false} otherwise
-	 *         indicating that {@link #lsRefs} must be called
-	 *
 	 * @throws org.eclipse.jgit.errors.TransportException
 	 *             the reference list could not be scanned.
 	 */
-	protected boolean readAdvertisedRefs() throws TransportException {
+	protected void readAdvertisedRefs() throws TransportException {
 		try {
-			return readAdvertisedRefsImpl();
+			readAdvertisedRefsImpl();
 		} catch (TransportException err) {
 			close();
 			throw err;
@@ -182,66 +156,35 @@ abstract class BasePackConnection extends BaseConnection {
 		}
 	}
 
-	private String readLine() throws IOException {
-		String line = pckIn.readString();
-		if (PacketLineIn.isEnd(line)) {
-			return null;
-		}
-		if (line.startsWith("ERR ")) { //$NON-NLS-1$
-			// This is a customized remote service error.
-			// Users should be informed about it.
-			throw new RemoteRepositoryException(uri, line.substring(4));
-		}
-		return line;
-	}
-
-	private boolean readAdvertisedRefsImpl() throws IOException {
+	private void readAdvertisedRefsImpl() throws IOException {
 		final LinkedHashMap<String, Ref> avail = new LinkedHashMap<>();
-		for (boolean first = true;; first = false) {
+		for (;;) {
 			String line;
 
-			if (first) {
-				boolean isV1 = false;
-				try {
-					line = readLine();
-				} catch (EOFException e) {
+			try {
+				line = pckIn.readString();
+			} catch (EOFException eof) {
+				if (avail.isEmpty())
 					throw noRepository();
-				}
-				if (line != null && VERSION_1.equals(line)) {
-					// Same as V0, except for this extra line. We shouldn't get
-					// it since we never request V1.
-					setProtocolVersion(TransferConfig.ProtocolVersion.V0);
-					isV1 = true;
-					line = readLine();
-				}
-				if (line == null) {
-					break;
-				}
+				throw eof;
+			}
+			if (PacketLineIn.isEnd(line))
+				break;
+
+			if (line.startsWith("ERR ")) { //$NON-NLS-1$
+				// This is a customized remote service error.
+				// Users should be informed about it.
+				throw new RemoteRepositoryException(uri, line.substring(4));
+			}
+
+			if (avail.isEmpty()) {
 				final int nul = line.indexOf('\0');
 				if (nul >= 0) {
-					// Protocol V0: The first line (if any) may contain
-					// "hidden" capability values after a NUL byte.
-					for (String capability : line.substring(nul + 1)
-							.split(" ")) { //$NON-NLS-1$
-						addCapability(capability);
-					}
+					// The first line (if any) may contain "hidden"
+					// capability values after a NUL byte.
+					remoteCapablities.addAll(
+							Arrays.asList(line.substring(nul + 1).split(" "))); //$NON-NLS-1$
 					line = line.substring(0, nul);
-					setProtocolVersion(TransferConfig.ProtocolVersion.V0);
-				} else if (!isV1 && VERSION_2.equals(line)) {
-					// Protocol V2: remaining lines are capabilities as
-					// key=value pairs
-					setProtocolVersion(TransferConfig.ProtocolVersion.V2);
-					readCapabilitiesV2();
-					// Break out here so that stateless RPC transports get a
-					// chance to set up the output stream.
-					return false;
-				} else {
-					setProtocolVersion(TransferConfig.ProtocolVersion.V0);
-				}
-			} else {
-				line = readLine();
-				if (line == null) {
-					break;
 				}
 			}
 
@@ -250,230 +193,44 @@ abstract class BasePackConnection extends BaseConnection {
 				throw invalidRefAdvertisementLine(line);
 			}
 			String name = line.substring(41, line.length());
-			if (first && name.equals("capabilities^{}")) { //$NON-NLS-1$
-				// special line from git-receive-pack (protocol V0) to show
+			if (avail.isEmpty() && name.equals("capabilities^{}")) { //$NON-NLS-1$
+				// special line from git-receive-pack to show
 				// capabilities when there are no refs to advertise
-				// TODO: throw error if protocol version is >= V2?
 				continue;
 			}
 
-			final ObjectId id = toId(line, line.substring(0, 40));
+			final ObjectId id;
+			try {
+				id  = ObjectId.fromString(line.substring(0, 40));
+			} catch (InvalidObjectIdException e) {
+				PackProtocolException ppe = invalidRefAdvertisementLine(line);
+				ppe.initCause(e);
+				throw ppe;
+			}
 			if (name.equals(".have")) { //$NON-NLS-1$
 				additionalHaves.add(id);
-			} else {
-				processLineV1(name, id, avail);
-			}
-		}
-		available(avail);
-		return true;
-	}
+			} else if (name.endsWith("^{}")) { //$NON-NLS-1$
+				name = name.substring(0, name.length() - 3);
+				final Ref prior = avail.get(name);
+				if (prior == null)
+					throw new PackProtocolException(uri, MessageFormat.format(
+							JGitText.get().advertisementCameBefore, name, name));
 
-	/**
-	 * Issue a protocol V2 ls-refs command and read its response.
-	 *
-	 * @param refSpecs
-	 *            to produce ref prefixes from if the server supports git
-	 *            protocol V2
-	 * @param additionalPatterns
-	 *            to use for ref prefixes if the server supports git protocol V2
-	 * @throws TransportException
-	 *             if the command could not be run or its output not be read
-	 */
-	protected void lsRefs(Collection<RefSpec> refSpecs,
-			String... additionalPatterns) throws TransportException {
-		try {
-			lsRefsImpl(refSpecs, additionalPatterns);
-		} catch (TransportException err) {
-			close();
-			throw err;
-		} catch (IOException | RuntimeException err) {
-			close();
-			throw new TransportException(err.getMessage(), err);
-		}
-	}
+				if (prior.getPeeledObjectId() != null)
+					throw duplicateAdvertisement(name + "^{}"); //$NON-NLS-1$
 
-	private void lsRefsImpl(Collection<RefSpec> refSpecs,
-			String... additionalPatterns) throws IOException {
-		TemporaryBuffer state = null;
-		PacketLineOut pckState = null;
-		PacketLineOut output = pckOut;
-		if (statelessRPC) {
-			state = new TemporaryBuffer.Heap(Integer.MAX_VALUE);
-			pckState = new PacketLineOut(state);
-			output = pckState;
-		}
-		output.writeString("command=" + COMMAND_LS_REFS); //$NON-NLS-1$
-		// Add the user-agent
-		String agent = UserAgent.get();
-		if (agent != null && isCapableOf(OPTION_AGENT)) {
-			output.writeString(OPTION_AGENT + '=' + agent);
-		}
-		output.writeDelim();
-		output.writeString("peel"); //$NON-NLS-1$
-		for (String refPrefix : getRefPrefixes(refSpecs, additionalPatterns)) {
-			output.writeString("ref-prefix " + refPrefix); //$NON-NLS-1$
-		}
-		output.end();
-		output.flush();
-		if (state != null) {
-			state.writeTo(out, null);
-			out.flush();
-			state = null;
-			pckState = null;
-		}
-		final LinkedHashMap<String, Ref> avail = new LinkedHashMap<>();
-		for (;;) {
-			String line = readLine();
-			if (line == null) {
-				break;
-			}
-			// Expecting to get a line in the form "sha1 refname"
-			if (line.length() < 41 || line.charAt(40) != ' ') {
-				throw invalidRefAdvertisementLine(line);
-			}
-			String name = line.substring(41, line.length());
-			final ObjectId id = toId(line, line.substring(0, 40));
-			if (name.equals(".have")) { //$NON-NLS-1$
-				additionalHaves.add(id);
+				avail.put(name, new ObjectIdRef.PeeledTag(
+						Ref.Storage.NETWORK, name, prior.getObjectId(), id));
 			} else {
-				processLineV2(line, id, name, avail);
+				final Ref prior = avail.put(name, new ObjectIdRef.PeeledNonTag(
+						Ref.Storage.NETWORK, name, id));
+				if (prior != null)
+					throw duplicateAdvertisement(name);
 			}
 		}
 		available(avail);
 	}
 
-	private Collection<String> getRefPrefixes(Collection<RefSpec> refSpecs,
-			String... additionalPatterns) {
-		if (refSpecs.isEmpty() && (additionalPatterns == null
-				|| additionalPatterns.length == 0)) {
-			return Collections.emptyList();
-		}
-		Set<String> patterns = new HashSet<>();
-		if (additionalPatterns != null) {
-			Arrays.stream(additionalPatterns).filter(Objects::nonNull)
-					.forEach(patterns::add);
-		}
-		for (RefSpec spec : refSpecs) {
-			// TODO: for now we only do protocol V2 for fetch. For push
-			// RefSpecs, the logic would need to be different. (At the
-			// minimum, take spec.getDestination().)
-			String src = spec.getSource();
-			if (ObjectId.isId(src)) {
-				continue;
-			}
-			if (spec.isWildcard()) {
-				patterns.add(src.substring(0, src.indexOf('*')));
-			} else {
-				patterns.add(src);
-				patterns.add(Constants.R_REFS + src);
-				patterns.add(Constants.R_HEADS + src);
-				patterns.add(Constants.R_TAGS + src);
-			}
-		}
-		return patterns;
-	}
-
-	private void readCapabilitiesV2() throws IOException {
-		// In git protocol V2, capabilities are different. If it's a key-value
-		// pair, the key may be a command name, and the value a space-separated
-		// list of capabilities for that command. We still store it in the same
-		// map as for protocol v0/v1. Protocol v2 code has to account for this.
-		for (;;) {
-			String line = readLine();
-			if (line == null) {
-				break;
-			}
-			addCapability(line);
-		}
-	}
-
-	private void addCapability(String capability) {
-		String parts[] = capability.split("=", 2); //$NON-NLS-1$
-		if (parts.length == 2) {
-			remoteCapabilities.put(parts[0], parts[1]);
-		}
-		remoteCapabilities.put(capability, null);
-	}
-
-	private ObjectId toId(String line, String value)
-			throws PackProtocolException {
-		try {
-			return ObjectId.fromString(value);
-		} catch (InvalidObjectIdException e) {
-			PackProtocolException ppe = invalidRefAdvertisementLine(line);
-			ppe.initCause(e);
-			throw ppe;
-		}
-	}
-
-	private void processLineV1(String name, ObjectId id, Map<String, Ref> avail)
-			throws IOException {
-		if (name.endsWith("^{}")) { //$NON-NLS-1$
-			name = name.substring(0, name.length() - 3);
-			final Ref prior = avail.get(name);
-			if (prior == null) {
-				throw new PackProtocolException(uri, MessageFormat.format(
-						JGitText.get().advertisementCameBefore, name, name));
-			}
-			if (prior.getPeeledObjectId() != null) {
-				throw duplicateAdvertisement(name + "^{}"); //$NON-NLS-1$
-			}
-			avail.put(name, new ObjectIdRef.PeeledTag(Ref.Storage.NETWORK, name,
-					prior.getObjectId(), id));
-		} else {
-			final Ref prior = avail.put(name, new ObjectIdRef.PeeledNonTag(
-					Ref.Storage.NETWORK, name, id));
-			if (prior != null) {
-				throw duplicateAdvertisement(name);
-			}
-		}
-	}
-
-	private void processLineV2(String line, ObjectId id, String rest,
-			Map<String, Ref> avail) throws IOException {
-		String[] parts = rest.split(" "); //$NON-NLS-1$
-		String name = parts[0];
-		// Two attributes possible, symref-target or peeled
-		String symRefTarget = null;
-		String peeled = null;
-		for (int i = 1; i < parts.length; i++) {
-			if (parts[i].startsWith(REF_ATTR_SYMREF_TARGET)) {
-				if (symRefTarget != null) {
-					throw new PackProtocolException(uri, MessageFormat.format(
-							JGitText.get().duplicateRefAttribute, line));
-				}
-				symRefTarget = parts[i]
-						.substring(REF_ATTR_SYMREF_TARGET.length());
-			} else if (parts[i].startsWith(REF_ATTR_PEELED)) {
-				if (peeled != null) {
-					throw new PackProtocolException(uri, MessageFormat.format(
-							JGitText.get().duplicateRefAttribute, line));
-				}
-				peeled = parts[i].substring(REF_ATTR_PEELED.length());
-			}
-			if (peeled != null && symRefTarget != null) {
-				break;
-			}
-		}
-		Ref idRef;
-		if (peeled != null) {
-			idRef = new ObjectIdRef.PeeledTag(Ref.Storage.NETWORK, name, id,
-					toId(line, peeled));
-		} else {
-			idRef = new ObjectIdRef.PeeledNonTag(Ref.Storage.NETWORK, name, id);
-		}
-		Ref prior = avail.put(name, idRef);
-		if (prior != null) {
-			throw duplicateAdvertisement(name);
-		}
-		if (symRefTarget != null) {
-			// What do we have to do with this information? In protocol V0, this
-			// info comes in the capability advertisement, but OPTION_SYMREF is
-			// used only in RefAdvertiser. JGit's client side doesn't make use
-			// of this information, and actually never requests it.
-		}
-	}
-
 	/**
 	 * Create an exception to indicate problems finding a remote repository. The
 	 * caller is expected to throw the returned exception.
@@ -495,7 +252,7 @@ abstract class BasePackConnection extends BaseConnection {
 	 * @return whether this option is supported
 	 */
 	protected boolean isCapableOf(String option) {
-		return remoteCapabilities.containsKey(option);
+		return remoteCapablities.contains(option);
 	}
 
 	/**
@@ -516,17 +273,6 @@ abstract class BasePackConnection extends BaseConnection {
 	}
 
 	/**
-	 * Return a capability value.
-	 *
-	 * @param option
-	 *            to get
-	 * @return the value stored, if any.
-	 */
-	protected String getCapability(String option) {
-		return remoteCapabilities.get(option);
-	}
-
-	/**
 	 * Add user agent capability
 	 *
 	 * @param b
@@ -534,7 +280,7 @@ abstract class BasePackConnection extends BaseConnection {
 	 */
 	protected void addUserAgentCapability(StringBuilder b) {
 		String a = UserAgent.get();
-		if (a != null && remoteCapabilities.get(OPTION_AGENT) != null) {
+		if (a != null && UserAgent.hasAgent(remoteCapablities)) {
 			b.append(' ').append(OPTION_AGENT).append('=').append(a);
 		}
 	}
@@ -542,8 +288,7 @@ abstract class BasePackConnection extends BaseConnection {
 	/** {@inheritDoc} */
 	@Override
 	public String getPeerUserAgent() {
-		String agent = remoteCapabilities.get(OPTION_AGENT);
-		return agent != null ? agent : super.getPeerUserAgent();
+		return UserAgent.getAgent(remoteCapablities, super.getPeerUserAgent());
 	}
 
 	private PackProtocolException duplicateAdvertisement(String name) {
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/BasePackFetchConnection.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/BasePackFetchConnection.java
index 2432641ede..a2fb51f46d 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/BasePackFetchConnection.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/BasePackFetchConnection.java
@@ -16,12 +16,9 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.text.MessageFormat;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Date;
-import java.util.HashSet;
-import java.util.LinkedHashSet;
 import java.util.Set;
 
 import org.eclipse.jgit.errors.PackProtocolException;
@@ -215,8 +212,6 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 
 	private PacketLineOut pckState;
 
-	private Set<String> fetchCapabilities = new HashSet<>();
-
 	/**
 	 * Either FilterSpec.NO_FILTER for a filter that doesn't filter
 	 * anything, or a filter that indicates what and what not to send to the
@@ -359,28 +354,6 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 				pckState = new PacketLineOut(state);
 			}
 
-			if (TransferConfig.ProtocolVersion.V2
-					.equals(getProtocolVersion())) {
-				sideband = true;
-				noDone = true;
-				multiAck = MultiAck.DETAILED;
-				setFetchOptions();
-				PacketLineOut output = statelessRPC ? pckState : pckOut;
-				output.writeString(
-						"command=" + GitProtocolConstants.COMMAND_FETCH); //$NON-NLS-1$
-				// Capabilities are sent as command arguments in protocol V2
-				String agent = UserAgent.get();
-				if (agent != null
-						&& isCapableOf(GitProtocolConstants.OPTION_AGENT)) {
-					output.writeString(
-							GitProtocolConstants.OPTION_AGENT + '=' + agent);
-				}
-				output.writeDelim();
-				// Arguments
-				for (String capability : getCapabilitiesV2()) {
-					output.writeString(capability);
-				}
-			}
 			if (sendWants(want)) {
 				negotiate(monitor);
 
@@ -389,25 +362,6 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 				state = null;
 				pckState = null;
 
-				if (TransferConfig.ProtocolVersion.V2
-						.equals(getProtocolVersion())) {
-					String header = pckIn.readString();
-					if (PacketLineIn.isEnd(header)) {
-						// No packfile following.
-						return;
-					}
-
-					if (header.startsWith("ERR ")) { //$NON-NLS-1$
-						// Protocol V2 may give us an error here (for instance,
-						// invalid want)
-						throw new PackProtocolException(header.substring(4));
-					}
-					if (!GitProtocolConstants.SECTION_PACKFILE.equals(header)) {
-						throw new PackProtocolException(MessageFormat.format(
-								JGitText.get().expectedGot,
-								GitProtocolConstants.SECTION_PACKFILE, header));
-					}
-				}
 				receivePack(monitor, outputStream);
 			}
 		} catch (CancelledException ce) {
@@ -427,14 +381,6 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 		super.close();
 	}
 
-	private void setFetchOptions() {
-		String advertised = getCapability(GitProtocolConstants.COMMAND_FETCH);
-		if (advertised == null) {
-			return;
-		}
-		fetchCapabilities.addAll(Arrays.asList(advertised.split(" "))); //$NON-NLS-1$
-	}
-
 	FetchConfig getFetchConfig() {
 		return local.getConfig().get(FetchConfig::new);
 	}
@@ -533,11 +479,10 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 			final StringBuilder line = new StringBuilder(46);
 			line.append("want "); //$NON-NLS-1$
 			line.append(objectId.name());
-			if (first && TransferConfig.ProtocolVersion.V0
-					.equals(getProtocolVersion())) {
+			if (first) {
 				line.append(enableCapabilities());
+				first = false;
 			}
-			first = false;
 			line.append('\n');
 			p.writeString(line.toString());
 		}
@@ -547,35 +492,11 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 		if (!filterSpec.isNoOp()) {
 			p.writeString(filterSpec.filterLine());
 		}
-		if (TransferConfig.ProtocolVersion.V0.equals(getProtocolVersion())) {
-			p.end();
-			outNeedsEnd = false;
-		}
+		p.end();
+		outNeedsEnd = false;
 		return true;
 	}
 
-	private Set<String> getCapabilitiesV2() throws TransportException {
-		Set<String> capabilities = new LinkedHashSet<>();
-		if (noProgress) {
-			capabilities.add(OPTION_NO_PROGRESS);
-		}
-		if (includeTags) {
-			capabilities.add(OPTION_INCLUDE_TAG);
-		}
-		if (allowOfsDelta) {
-			capabilities.add(OPTION_OFS_DELTA);
-		}
-		if (thinPack) {
-			capabilities.add(OPTION_THIN_PACK);
-		}
-		if (!filterSpec.isNoOp()
-				&& !fetchCapabilities.contains(OPTION_FILTER)) {
-			throw new PackProtocolException(uri,
-					JGitText.get().filterRequiresCapability);
-		}
-		return capabilities;
-	}
-
 	private String enableCapabilities() throws TransportException {
 		final StringBuilder line = new StringBuilder();
 		if (noProgress)
@@ -629,7 +550,6 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 		boolean receivedContinue = false;
 		boolean receivedAck = false;
 		boolean receivedReady = false;
-		boolean needsAcknowledgementV2 = true;
 
 		if (statelessRPC) {
 			state.writeTo(out, null);
@@ -643,7 +563,7 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 			}
 
 			ObjectId o = c.getId();
-			pckOut.writeString("have " + o.name() + '\n'); //$NON-NLS-1$
+			pckOut.writeString("have " + o.name() + "\n"); //$NON-NLS-1$ //$NON-NLS-2$
 			havesSent++;
 			havesSinceLastContinue++;
 
@@ -660,7 +580,6 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 			}
 
 			pckOut.end();
-			outNeedsEnd = false;
 			resultsPending++; // Each end will cause a result to come back.
 
 			if (havesSent == 32 && !statelessRPC) {
@@ -672,32 +591,9 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 				continue;
 			}
 
-			// Read the section header
-			if (needsAcknowledgementV2 && TransferConfig.ProtocolVersion.V2
-					.equals(getProtocolVersion())) {
-				String header = pckIn.readString();
-				if (!GitProtocolConstants.SECTION_ACKNOWLEDGMENTS
-						.equals(header)) {
-					throw new PackProtocolException(MessageFormat.format(
-							JGitText.get().expectedGot,
-							GitProtocolConstants.SECTION_ACKNOWLEDGMENTS,
-							header));
-				}
-				needsAcknowledgementV2 = false;
-			}
 			READ_RESULT: for (;;) {
-				AckNackResult anr = pckIn.readACKorEOF(ackId);
+				final AckNackResult anr = pckIn.readACK(ackId);
 				switch (anr) {
-				case ACK_EOF:
-					if (TransferConfig.ProtocolVersion.V0
-							.equals(getProtocolVersion())) {
-						throw new PackProtocolException(
-								JGitText.get().expectedACKNAKFoundEOF);
-					}
-					// More lines needed
-					resultsPending--;
-					break READ_RESULT;
-
 				case NAK:
 					// More have lines are necessary to compute the
 					// pack on the remote side. Keep doing that.
@@ -706,24 +602,17 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 					break READ_RESULT;
 
 				case ACK:
-					if (TransferConfig.ProtocolVersion.V0
-							.equals(getProtocolVersion())) {
-						// The remote side is happy and knows exactly what
-						// to send us. There is no further negotiation and
-						// we can break out immediately.
-						//
-						multiAck = MultiAck.OFF;
-						resultsPending = 0;
-						receivedAck = true;
-						if (statelessRPC) {
-							state.writeTo(out, null);
-						}
-						break SEND_HAVES;
-					}
-					// Keep on reading ACKs until we get the ACK_READY
-					markCommon(walk.parseAny(ackId), AckNackResult.ACK_COMMON);
+					// The remote side is happy and knows exactly what
+					// to send us. There is no further negotiation and
+					// we can break out immediately.
+					//
+					multiAck = MultiAck.OFF;
+					resultsPending = 0;
 					receivedAck = true;
-					break;
+					if (statelessRPC) {
+						state.writeTo(out, null);
+					}
+					break SEND_HAVES;
 
 				case ACK_CONTINUE:
 				case ACK_COMMON:
@@ -739,12 +628,6 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 					havesSinceLastContinue = 0;
 					if (anr == AckNackResult.ACK_READY) {
 						receivedReady = true;
-						if (TransferConfig.ProtocolVersion.V2
-								.equals(getProtocolVersion())) {
-							multiAck = MultiAck.OFF;
-							resultsPending = 0;
-							break SEND_HAVES;
-						}
 					}
 					break;
 				}
@@ -778,36 +661,15 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 			throw new CancelledException();
 		}
 
-		if (receivedReady && TransferConfig.ProtocolVersion.V2
-				.equals(getProtocolVersion())) {
-			// We'll get the packfile right away. Skip the delimiter.
-			String delim = pckIn.readString();
-			if (!PacketLineIn.isDelimiter(delim)) {
-				throw new PackProtocolException(MessageFormat
-						.format(JGitText.get().expectedGot, "0001", delim)); //$NON-NLS-1$
-			}
-			return;
-		}
 		if (!receivedReady || !noDone) {
 			// When statelessRPC is true we should always leave SEND_HAVES
 			// loop above while in the middle of a request. This allows us
 			// to just write done immediately.
 			//
 			pckOut.writeString("done\n"); //$NON-NLS-1$
-			if (TransferConfig.ProtocolVersion.V2
-					.equals(getProtocolVersion())) {
-				pckOut.end();
-				outNeedsEnd = false;
-				pckOut.flush();
-				// Protocol V2 will skip acknowledgments completely if we send
-				// a done.
-				return;
-			}
 			pckOut.flush();
 		}
 
-		// Below is protocol V0 only.
-
 		if (!receivedAck) {
 			// Apparently if we have never received an ACK earlier
 			// there is one more result expected from the done we
@@ -827,14 +689,6 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 				//
 				break;
 
-			case ACK_EOF:
-				if (TransferConfig.ProtocolVersion.V0
-						.equals(getProtocolVersion())) {
-					throw new PackProtocolException(
-							JGitText.get().expectedACKNAKFoundEOF);
-				}
-				break READ_RESULT;
-
 			case ACK:
 				// A solitary ACK at this point means the remote won't
 				// speak anymore, but is going to send us a pack now.
@@ -843,16 +697,7 @@ public abstract class BasePackFetchConnection extends BasePackConnection
 
 			case ACK_CONTINUE:
 			case ACK_COMMON:
-				// We will expect a normal ACK to break out of the loop.
-				//
-				multiAck = MultiAck.CONTINUE;
-				break;
-
 			case ACK_READY:
-				if (TransferConfig.ProtocolVersion.V2
-						.equals(getProtocolVersion())) {
-					break READ_RESULT;
-				}
 				// We will expect a normal ACK to break out of the loop.
 				//
 				multiAck = MultiAck.CONTINUE;
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/FetchProcess.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/FetchProcess.java
index b9b764c9d0..0f1892a97e 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/FetchProcess.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/FetchProcess.java
@@ -102,21 +102,7 @@ class FetchProcess {
 	private void executeImp(final ProgressMonitor monitor,
 			final FetchResult result) throws NotSupportedException,
 			TransportException {
-		final TagOpt tagopt = transport.getTagOpt();
-		String getTags = (tagopt == TagOpt.NO_TAGS) ? null : Constants.R_TAGS;
-		String getHead = null;
-		try {
-			// If we don't have a HEAD yet, we're cloning and need to get the
-			// upstream HEAD, too.
-			Ref head = transport.local.exactRef(Constants.HEAD);
-			ObjectId id = head != null ? head.getObjectId() : null;
-			if (id == null || id.equals(ObjectId.zeroId())) {
-				getHead = Constants.HEAD;
-			}
-		} catch (IOException e) {
-			// Ignore
-		}
-		conn = transport.openFetch(toFetch, getTags, getHead);
+		conn = transport.openFetch();
 		try {
 			result.setAdvertisedRefs(transport.getURI(), conn.getRefsMap());
 			result.peerUserAgent = conn.getPeerUserAgent();
@@ -133,6 +119,7 @@ class FetchProcess {
 			}
 
 			Collection<Ref> additionalTags = Collections.<Ref> emptyList();
+			final TagOpt tagopt = transport.getTagOpt();
 			if (tagopt == TagOpt.AUTO_FOLLOW)
 				additionalTags = expandAutoFollowTags();
 			else if (tagopt == TagOpt.FETCH_TAGS)
@@ -266,17 +253,7 @@ class FetchProcess {
 		if (conn != null)
 			return;
 
-		// Build prefixes
-		Set<String> prefixes = new HashSet<>();
-		for (Ref toGet : askFor.values()) {
-			String src = toGet.getName();
-			prefixes.add(src);
-			prefixes.add(Constants.R_REFS + src);
-			prefixes.add(Constants.R_HEADS + src);
-			prefixes.add(Constants.R_TAGS + src);
-		}
-		conn = transport.openFetch(Collections.emptyList(),
-				prefixes.toArray(new String[0]));
+		conn = transport.openFetch();
 
 		// Since we opened a new connection we cannot be certain
 		// that the system we connected to has the same exact set
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/GitProtocolConstants.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/GitProtocolConstants.java
index ea6dec8ee7..35e2978bc4 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/GitProtocolConstants.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/GitProtocolConstants.java
@@ -247,74 +247,6 @@ public final class GitProtocolConstants {
 	 */
 	public static final String COMMAND_FETCH = "fetch"; //$NON-NLS-1$
 
-	/**
-	 * HTTP header to set by clients to request a specific git protocol version
-	 * in the HTTP transport.
-	 *
-	 * @since 5.10
-	 */
-	public static final String PROTOCOL_HEADER = "Git-Protocol"; //$NON-NLS-1$
-
-	/**
-	 * Environment variable to set by clients to request a specific git protocol
-	 * in the file:// and ssh:// transports.
-	 *
-	 * @since 5.10
-	 */
-	public static final String PROTOCOL_ENVIRONMENT_VARIABLE = "GIT_PROTOCOL"; //$NON-NLS-1$
-
-	/**
-	 * Protocol V2 ref advertisement attribute containing the peeled object id
-	 * for annotated tags.
-	 *
-	 * @since 5.10
-	 */
-	public static final String REF_ATTR_PEELED = "peeled:"; //$NON-NLS-1$
-
-	/**
-	 * Protocol V2 ref advertisement attribute containing the name of the ref
-	 * for symbolic refs.
-	 *
-	 * @since 5.10
-	 */
-	public static final String REF_ATTR_SYMREF_TARGET = "symref-target:"; //$NON-NLS-1$
-
-	/**
-	 * Protocol V2 acknowledgments section header.
-	 *
-	 * @since 5.10
-	 */
-	public static final String SECTION_ACKNOWLEDGMENTS = "acknowledgments"; //$NON-NLS-1$
-
-	/**
-	 * Protocol V2 packfile section header.
-	 *
-	 * @since 5.10
-	 */
-	public static final String SECTION_PACKFILE = "packfile"; //$NON-NLS-1$
-
-	/**
-	 * Protocol announcement for protocol version 1. This is the same as V0,
-	 * except for this initial line.
-	 *
-	 * @since 5.10
-	 */
-	public static final String VERSION_1 = "version 1"; //$NON-NLS-1$
-
-	/**
-	 * Protocol announcement for protocol version 2.
-	 *
-	 * @since 5.10
-	 */
-	public static final String VERSION_2 = "version 2"; //$NON-NLS-1$
-
-	/**
-	 * Protocol request for protocol version 2.
-	 *
-	 * @since 5.10
-	 */
-	public static final String VERSION_2_REQUEST = "version=2"; //$NON-NLS-1$
-
 	enum MultiAck {
 		OFF, CONTINUE, DETAILED;
 	}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineIn.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineIn.java
index 32046dc434..52a5576e43 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineIn.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineIn.java
@@ -72,9 +72,7 @@ public class PacketLineIn {
 		/** ACK + common */
 		ACK_COMMON,
 		/** ACK + ready */
-		ACK_READY,
-		/** EOF (0000) recieved in protocol V2 when expecting an ACK/NAK */
-		ACK_EOF;
+		ACK_READY;
 	}
 
 	private final byte[] lineBuffer = new byte[SideBandOutputStream.SMALL_BUF];
@@ -105,26 +103,12 @@ public class PacketLineIn {
 		this.limit = limit;
 	}
 
-
 	AckNackResult readACK(MutableObjectId returnedId) throws IOException {
-		AckNackResult result = readACKorEOF(returnedId);
-		if (result == AckNackResult.ACK_EOF) {
-			throw new PackProtocolException(
-					JGitText.get().expectedACKNAKFoundEOF);
-		}
-		return result;
-	}
-
-	AckNackResult readACKorEOF(MutableObjectId returnedId) throws IOException {
 		final String line = readString();
 		if (line.length() == 0)
-			return AckNackResult.ACK_EOF;
+			throw new PackProtocolException(JGitText.get().expectedACKNAKFoundEOF);
 		if ("NAK".equals(line)) //$NON-NLS-1$
 			return AckNackResult.NAK;
-		if ("ready".equals(line)) { //$NON-NLS-1$
-			// Protocol V2
-			return AckNackResult.ACK_READY;
-		}
 		if (line.startsWith("ACK ")) { //$NON-NLS-1$
 			returnedId.fromString(line.substring(4, 44));
 			if (line.length() == 44)
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/RefAdvertiser.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/RefAdvertiser.java
index 3f50c57843..3adebba03c 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/RefAdvertiser.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/RefAdvertiser.java
@@ -13,8 +13,6 @@ package org.eclipse.jgit.transport;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.eclipse.jgit.lib.Constants.OBJECT_ID_STRING_LENGTH;
 import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SYMREF;
-import static org.eclipse.jgit.transport.GitProtocolConstants.REF_ATTR_PEELED;
-import static org.eclipse.jgit.transport.GitProtocolConstants.REF_ATTR_SYMREF_TARGET;
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
@@ -289,8 +287,7 @@ public abstract class RefAdvertiser {
 
 			if (useProtocolV2) {
 				String symrefPart = symrefs.containsKey(ref.getName())
-						? (' ' + REF_ATTR_SYMREF_TARGET
-								+ symrefs.get(ref.getName()))
+						? (" symref-target:" + symrefs.get(ref.getName())) //$NON-NLS-1$
 						: ""; //$NON-NLS-1$
 				String peelPart = ""; //$NON-NLS-1$
 				if (derefTags) {
@@ -299,8 +296,7 @@ public abstract class RefAdvertiser {
 					}
 					ObjectId peeledObjectId = ref.getPeeledObjectId();
 					if (peeledObjectId != null) {
-						peelPart = ' ' + REF_ATTR_PEELED
-								+ peeledObjectId.getName();
+						peelPart = " peeled:" + peeledObjectId.getName(); //$NON-NLS-1$
 					}
 				}
 				writeOne(objectId.getName() + " " + ref.getName() + symrefPart //$NON-NLS-1$
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/RemoteSession2.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/RemoteSession2.java
deleted file mode 100644
index 8119f75aaa..0000000000
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/RemoteSession2.java
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
- * Copyright (C) 2020, Thomas Wolf <thoams.wolf@paranor.ch>
- *
- * This program and the accompanying materials are made available under the
- * terms of the Eclipse Distribution License v. 1.0 which is available at
- * https://www.eclipse.org/org/documents/edl-v10.php.
- *
- * SPDX-License-Identifier: BSD-3-Clause
- */
-
-package org.eclipse.jgit.transport;
-
-import java.io.IOException;
-import java.util.Map;
-
-/**
- * A {@link RemoteSession} that supports passing environment variables to
- * commands.
- *
- * @since 5.10
- */
-public interface RemoteSession2 extends RemoteSession {
-
-	/**
-	 * Creates a new remote {@link Process} to execute the given command. The
-	 * returned process's streams exist and are connected, and execution of the
-	 * process is already started.
-	 *
-	 * @param commandName
-	 *            command to execute
-	 * @param environment
-	 *            environment variables to pass on
-	 * @param timeout
-	 *            timeout value, in seconds, for creating the remote process
-	 * @return a new remote process, already started
-	 * @throws java.io.IOException
-	 *             may be thrown in several cases. For example, on problems
-	 *             opening input or output streams or on problems connecting or
-	 *             communicating with the remote host. For the latter two cases,
-	 *             a TransportException may be thrown (a subclass of
-	 *             java.io.IOException).
-	 */
-	Process exec(String commandName, Map<String, String> environment,
-			int timeout) throws IOException;
-}
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/Transport.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/Transport.java
index f0f9e1db68..2ddd0a6128 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/Transport.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/Transport.java
@@ -39,7 +39,6 @@ import java.util.Vector;
 import java.util.concurrent.CopyOnWriteArrayList;
 
 import org.eclipse.jgit.annotations.NonNull;
-import org.eclipse.jgit.annotations.Nullable;
 import org.eclipse.jgit.api.errors.AbortedByHookException;
 import org.eclipse.jgit.errors.NotSupportedException;
 import org.eclipse.jgit.errors.TransportException;
@@ -775,10 +774,6 @@ public abstract class Transport implements AutoCloseable {
 	private PrintStream hookOutRedirect;
 
 	private PrePushHook prePush;
-
-	@Nullable
-	TransferConfig.ProtocolVersion protocol;
-
 	/**
 	 * Create a new transport instance.
 	 *
@@ -794,7 +789,6 @@ public abstract class Transport implements AutoCloseable {
 		final TransferConfig tc = local.getConfig().get(TransferConfig.KEY);
 		this.local = local;
 		this.uri = uri;
-		this.protocol = tc.protocolVersion;
 		this.objectChecker = tc.newObjectChecker();
 		this.credentialsProvider = CredentialsProvider.getDefault();
 		prePush = Hooks.prePush(local, hookOutRedirect);
@@ -1459,43 +1453,6 @@ public abstract class Transport implements AutoCloseable {
 			TransportException;
 
 	/**
-	 * Begins a new connection for fetching from the remote repository.
-	 * <p>
-	 * If the transport has no local repository, the fetch connection can only
-	 * be used for reading remote refs.
-	 * </p>
-	 * <p>
-	 * If the server supports git protocol V2, the {@link RefSpec}s and the
-	 * additional patterns, if any, are used to restrict the server's ref
-	 * advertisement to matching refs only.
-	 * </p>
-	 * <p>
-	 * Transports that want to support git protocol V2 <em>must</em> override
-	 * this; the default implementation ignores its arguments and calls
-	 * {@link #openFetch()}.
-	 * </p>
-	 *
-	 * @param refSpecs
-	 *            that will be fetched via
-	 *            {@link FetchConnection#fetch(ProgressMonitor, Collection, java.util.Set, OutputStream)} later
-	 * @param additionalPatterns
-	 *            that will be set as ref prefixes if the server supports git
-	 *            protocol V2; {@code null} values are ignored
-	 *
-	 * @return a fresh connection to fetch from the remote repository.
-	 * @throws org.eclipse.jgit.errors.NotSupportedException
-	 *             the implementation does not support fetching.
-	 * @throws org.eclipse.jgit.errors.TransportException
-	 *             the remote connection could not be established.
-	 * @since 5.10
-	 */
-	public FetchConnection openFetch(Collection<RefSpec> refSpecs,
-			String... additionalPatterns)
-			throws NotSupportedException, TransportException {
-		return openFetch();
-	}
-
-	/**
 	 * Begins a new connection for pushing into the remote repository.
 	 *
 	 * @return a fresh connection to push into the remote repository.
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportGitAnon.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportGitAnon.java
index 5913aa4e34..820ec1a67a 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportGitAnon.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportGitAnon.java
@@ -22,7 +22,6 @@ import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.Socket;
 import java.net.UnknownHostException;
-import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.Set;
@@ -95,13 +94,6 @@ class TransportGitAnon extends TcpTransport implements PackTransport {
 		return new TcpFetchConnection();
 	}
 
-	@Override
-	public FetchConnection openFetch(Collection<RefSpec> refSpecs,
-			String... additionalPatterns)
-			throws NotSupportedException, TransportException {
-		return new TcpFetchConnection(refSpecs, additionalPatterns);
-	}
-
 	/** {@inheritDoc} */
 	@Override
 	public PushConnection openPush() throws TransportException {
@@ -138,8 +130,7 @@ class TransportGitAnon extends TcpTransport implements PackTransport {
 		return s;
 	}
 
-	void service(String name, PacketLineOut pckOut,
-			TransferConfig.ProtocolVersion gitProtocol)
+	void service(String name, PacketLineOut pckOut)
 			throws IOException {
 		final StringBuilder cmd = new StringBuilder();
 		cmd.append(name);
@@ -153,11 +144,6 @@ class TransportGitAnon extends TcpTransport implements PackTransport {
 			cmd.append(uri.getPort());
 		}
 		cmd.append('\0');
-		if (TransferConfig.ProtocolVersion.V2.equals(gitProtocol)) {
-			cmd.append('\0');
-			cmd.append(GitProtocolConstants.VERSION_2_REQUEST);
-			cmd.append('\0');
-		}
 		pckOut.writeString(cmd.toString());
 		pckOut.flush();
 	}
@@ -166,11 +152,6 @@ class TransportGitAnon extends TcpTransport implements PackTransport {
 		private Socket sock;
 
 		TcpFetchConnection() throws TransportException {
-			this(Collections.emptyList());
-		}
-
-		TcpFetchConnection(Collection<RefSpec> refSpecs,
-				String... additionalPatterns) throws TransportException {
 			super(TransportGitAnon.this);
 			sock = openConnection();
 			try {
@@ -181,19 +162,13 @@ class TransportGitAnon extends TcpTransport implements PackTransport {
 				sOut = new BufferedOutputStream(sOut);
 
 				init(sIn, sOut);
-				TransferConfig.ProtocolVersion gitProtocol = protocol;
-				if (gitProtocol == null) {
-					gitProtocol = TransferConfig.ProtocolVersion.V2;
-				}
-				service("git-upload-pack", pckOut, gitProtocol); //$NON-NLS-1$
+				service("git-upload-pack", pckOut); //$NON-NLS-1$
 			} catch (IOException err) {
 				close();
 				throw new TransportException(uri,
 						JGitText.get().remoteHungUpUnexpectedly, err);
 			}
-			if (!readAdvertisedRefs()) {
-				lsRefs(refSpecs, additionalPatterns);
-			}
+			readAdvertisedRefs();
 		}
 
 		@Override
@@ -226,7 +201,7 @@ class TransportGitAnon extends TcpTransport implements PackTransport {
 				sOut = new BufferedOutputStream(sOut);
 
 				init(sIn, sOut);
-				service("git-receive-pack", pckOut, null); //$NON-NLS-1$
+				service("git-receive-pack", pckOut); //$NON-NLS-1$
 			} catch (IOException err) {
 				close();
 				throw new TransportException(uri,
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportGitSsh.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportGitSsh.java
index 6aa2e0bedc..b9cb2484d8 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportGitSsh.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportGitSsh.java
@@ -19,13 +19,11 @@ import java.io.InputStream;
 import java.text.MessageFormat;
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumSet;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Locale;
-import java.util.Map;
 import java.util.Set;
 
 import org.eclipse.jgit.errors.NoRemoteRepositoryException;
@@ -146,13 +144,6 @@ public class TransportGitSsh extends SshTransport implements PackTransport {
 		return new SshFetchConnection();
 	}
 
-	@Override
-	public FetchConnection openFetch(Collection<RefSpec> refSpecs,
-			String... additionalPatterns)
-			throws NotSupportedException, TransportException {
-		return new SshFetchConnection(refSpecs, additionalPatterns);
-	}
-
 	/** {@inheritDoc} */
 	@Override
 	public PushConnection openPush() throws TransportException {
@@ -205,38 +196,29 @@ public class TransportGitSsh extends SshTransport implements PackTransport {
 		return SystemReader.getInstance().getenv("GIT_SSH") != null; //$NON-NLS-1$
 	}
 
-	private class ExtSession implements RemoteSession2 {
-
+	private class ExtSession implements RemoteSession {
 		@Override
 		public Process exec(String command, int timeout)
 				throws TransportException {
-			return exec(command, null, timeout);
-		}
-
-		@Override
-		public Process exec(String command, Map<String, String> environment,
-				int timeout) throws TransportException {
 			String ssh = SystemReader.getInstance().getenv("GIT_SSH"); //$NON-NLS-1$
 			boolean putty = ssh.toLowerCase(Locale.ROOT).contains("plink"); //$NON-NLS-1$
 
 			List<String> args = new ArrayList<>();
 			args.add(ssh);
-			if (putty && !ssh.toLowerCase(Locale.ROOT)
-					.contains("tortoiseplink")) {//$NON-NLS-1$
+			if (putty
+					&& !ssh.toLowerCase(Locale.ROOT).contains("tortoiseplink")) //$NON-NLS-1$
 				args.add("-batch"); //$NON-NLS-1$
-			}
 			if (0 < getURI().getPort()) {
 				args.add(putty ? "-P" : "-p"); //$NON-NLS-1$ //$NON-NLS-2$
 				args.add(String.valueOf(getURI().getPort()));
 			}
-			if (getURI().getUser() != null) {
+			if (getURI().getUser() != null)
 				args.add(getURI().getUser() + "@" + getURI().getHost()); //$NON-NLS-1$
-			} else {
+			else
 				args.add(getURI().getHost());
-			}
 			args.add(command);
 
-			ProcessBuilder pb = createProcess(args, environment);
+			ProcessBuilder pb = createProcess(args);
 			try {
 				return pb.start();
 			} catch (IOException err) {
@@ -244,13 +226,9 @@ public class TransportGitSsh extends SshTransport implements PackTransport {
 			}
 		}
 
-		private ProcessBuilder createProcess(List<String> args,
-				Map<String, String> environment) {
+		private ProcessBuilder createProcess(List<String> args) {
 			ProcessBuilder pb = new ProcessBuilder();
 			pb.command(args);
-			if (environment != null) {
-				pb.environment().putAll(environment);
-			}
 			File directory = local != null ? local.getDirectory() : null;
 			if (directory != null) {
 				pb.environment().put(Constants.GIT_DIR_KEY,
@@ -271,31 +249,10 @@ public class TransportGitSsh extends SshTransport implements PackTransport {
 		private StreamCopyThread errorThread;
 
 		SshFetchConnection() throws TransportException {
-			this(Collections.emptyList());
-		}
-
-		SshFetchConnection(Collection<RefSpec> refSpecs,
-				String... additionalPatterns) throws TransportException {
 			super(TransportGitSsh.this);
 			try {
-				RemoteSession session = getSession();
-				TransferConfig.ProtocolVersion gitProtocol = protocol;
-				if (gitProtocol == null) {
-					gitProtocol = TransferConfig.ProtocolVersion.V2;
-				}
-				if (session instanceof RemoteSession2
-						&& TransferConfig.ProtocolVersion.V2
-								.equals(gitProtocol)) {
-					process = ((RemoteSession2) session).exec(
-							commandFor(getOptionUploadPack()), Collections
-									.singletonMap(
-											GitProtocolConstants.PROTOCOL_ENVIRONMENT_VARIABLE,
-											GitProtocolConstants.VERSION_2_REQUEST),
-							getTimeout());
-				} else {
-					process = session.exec(commandFor(getOptionUploadPack()),
-							getTimeout());
-				}
+				process = getSession().exec(commandFor(getOptionUploadPack()),
+						getTimeout());
 				final MessageWriter msg = new MessageWriter();
 				setMessageWriter(msg);
 
@@ -315,9 +272,7 @@ public class TransportGitSsh extends SshTransport implements PackTransport {
 			}
 
 			try {
-				if (!readAdvertisedRefs()) {
-					lsRefs(refSpecs, additionalPatterns);
-				}
+				readAdvertisedRefs();
 			} catch (NoRemoteRepositoryException notFound) {
 				final String msgs = getMessages();
 				checkExecFailure(process.exitValue(), getOptionUploadPack(),
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportHttp.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportHttp.java
index 77a7a46402..6768387e65 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportHttp.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportHttp.java
@@ -33,8 +33,8 @@ import static org.eclipse.jgit.util.HttpSupport.HDR_WWW_AUTHENTICATE;
 import static org.eclipse.jgit.util.HttpSupport.METHOD_GET;
 import static org.eclipse.jgit.util.HttpSupport.METHOD_POST;
 
-import java.io.BufferedInputStream;
 import java.io.BufferedReader;
+import java.io.ByteArrayInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
@@ -339,15 +339,11 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 
 	@SuppressWarnings("resource") // Closed by caller
 	private FetchConnection getConnection(HttpConnection c, InputStream in,
-			String service, Collection<RefSpec> refSpecs,
-			String... additionalPatterns) throws IOException {
+			String service) throws IOException {
 		BaseConnection f;
 		if (isSmartHttp(c, service)) {
-			InputStream withMark = in.markSupported() ? in
-					: new BufferedInputStream(in);
-			readSmartHeaders(withMark, service);
-			f = new SmartHttpFetchConnection(withMark, refSpecs,
-					additionalPatterns);
+			readSmartHeaders(in, service);
+			f = new SmartHttpFetchConnection(in);
 		} else {
 			// Assume this server doesn't support smart HTTP fetch
 			// and fall back on dumb object walking.
@@ -361,23 +357,11 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 	@Override
 	public FetchConnection openFetch() throws TransportException,
 			NotSupportedException {
-		return openFetch(Collections.emptyList());
-	}
-
-	@Override
-	public FetchConnection openFetch(Collection<RefSpec> refSpecs,
-			String... additionalPatterns)
-			throws NotSupportedException, TransportException {
 		final String service = SVC_UPLOAD_PACK;
 		try {
-			TransferConfig.ProtocolVersion gitProtocol = protocol;
-			if (gitProtocol == null) {
-				gitProtocol = TransferConfig.ProtocolVersion.V2;
-			}
-			HttpConnection c = connect(service, gitProtocol);
+			final HttpConnection c = connect(service);
 			try (InputStream in = openInputStream(c)) {
-				return getConnection(c, in, service, refSpecs,
-						additionalPatterns);
+				return getConnection(c, in, service);
 			}
 		} catch (NotSupportedException | TransportException err) {
 			throw err;
@@ -472,9 +456,8 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 
 	private PushConnection smartPush(String service, HttpConnection c,
 			InputStream in) throws IOException, TransportException {
-		BufferedInputStream inBuf = new BufferedInputStream(in);
-		readSmartHeaders(inBuf, service);
-		SmartHttpPushConnection p = new SmartHttpPushConnection(inBuf);
+		readSmartHeaders(in, service);
+		SmartHttpPushConnection p = new SmartHttpPushConnection(in);
 		p.setPeerUserAgent(c.getHeaderField(HttpSupport.HDR_SERVER));
 		return p;
 	}
@@ -511,12 +494,6 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 
 	private HttpConnection connect(String service)
 			throws TransportException, NotSupportedException {
-		return connect(service, null);
-	}
-
-	private HttpConnection connect(String service,
-			TransferConfig.ProtocolVersion protocolVersion)
-			throws TransportException, NotSupportedException {
 		URL u = getServiceURL(service);
 		int authAttempts = 1;
 		int redirects = 0;
@@ -530,11 +507,6 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 				} else {
 					conn.setRequestProperty(HDR_ACCEPT, "*/*"); //$NON-NLS-1$
 				}
-				if (TransferConfig.ProtocolVersion.V2.equals(protocolVersion)) {
-					conn.setRequestProperty(
-							GitProtocolConstants.PROTOCOL_HEADER,
-							GitProtocolConstants.VERSION_2_REQUEST);
-				}
 				final int status = HttpSupport.response(conn);
 				processResponseCookies(conn);
 				switch (status) {
@@ -1176,37 +1148,20 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 
 	private void readSmartHeaders(InputStream in, String service)
 			throws IOException {
-		// A smart protocol V0 reply will have a '#' after the first 4 bytes,
-		// but a dumb reply cannot contain a '#' until after byte 41. Do a
+		// A smart reply will have a '#' after the first 4 bytes, but
+		// a dumb reply cannot contain a '#' until after byte 41. Do a
 		// quick check to make sure its a smart reply before we parse
 		// as a pkt-line stream.
 		//
-		// There appears to be a confusion about this in protocol V2. Github
-		// sends the # service line as a git (not http) header also when
-		// protocol V2 is used. Gitlab also does so. JGit's UploadPack doesn't,
-		// and thus Gerrit also does not.
-		final byte[] magic = new byte[14];
-		if (!in.markSupported()) {
-			throw new TransportException(uri,
-					JGitText.get().inputStreamMustSupportMark);
-		}
-		in.mark(14);
+		final byte[] magic = new byte[5];
 		IO.readFully(in, magic, 0, magic.length);
-		// Did we get 000dversion 2 or similar? (Canonical is 000eversion 2\n,
-		// but JGit and thus Gerrit omits the \n.)
-		if (Arrays.equals(Arrays.copyOfRange(magic, 4, 11),
-				"version".getBytes()) && magic[12] >= '1' && magic[12] <= '9') { //$NON-NLS-1$
-			// It's a smart server doing version 1 or greater, but not sending
-			// the # service line header. Don't consume the version line.
-			in.reset();
-			return;
-		}
 		if (magic[4] != '#') {
 			throw new TransportException(uri, MessageFormat.format(
 					JGitText.get().expectedPktLineWithService, RawParseUtils.decode(magic)));
 		}
-		in.reset();
-		final PacketLineIn pckIn = new PacketLineIn(in);
+
+		final PacketLineIn pckIn = new PacketLineIn(new UnionInputStream(
+				new ByteArrayInputStream(magic), in));
 		final String exp = "# service=" + service; //$NON-NLS-1$
 		final String act = pckIn.readString();
 		if (!exp.equals(act)) {
@@ -1372,24 +1327,12 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 
 		SmartHttpFetchConnection(InputStream advertisement)
 				throws TransportException {
-			this(advertisement, Collections.emptyList());
-		}
-
-		SmartHttpFetchConnection(InputStream advertisement,
-				Collection<RefSpec> refSpecs, String... additionalPatterns)
-				throws TransportException {
 			super(TransportHttp.this);
 			statelessRPC = true;
 
 			init(advertisement, DisabledOutputStream.INSTANCE);
 			outNeedsEnd = false;
-			if (!readAdvertisedRefs()) {
-				// Must be protocol V2
-				LongPollService service = new LongPollService(SVC_UPLOAD_PACK,
-						getProtocolVersion());
-				init(service.getInputStream(), service.getOutputStream());
-				lsRefs(refSpecs, additionalPatterns);
-			}
+			readAdvertisedRefs();
 		}
 
 		@Override
@@ -1397,8 +1340,7 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 				final Collection<Ref> want, final Set<ObjectId> have,
 				final OutputStream outputStream) throws TransportException {
 			try {
-				svc = new MultiRequestService(SVC_UPLOAD_PACK,
-						getProtocolVersion());
+				svc = new MultiRequestService(SVC_UPLOAD_PACK);
 				init(svc.getInputStream(), svc.getOutputStream());
 				super.doFetch(monitor, want, have, outputStream);
 			} finally {
@@ -1427,8 +1369,7 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 		protected void doPush(final ProgressMonitor monitor,
 				final Map<String, RemoteRefUpdate> refUpdates,
 				OutputStream outputStream) throws TransportException {
-			final Service svc = new MultiRequestService(SVC_RECEIVE_PACK,
-					getProtocolVersion());
+			final Service svc = new MultiRequestService(SVC_RECEIVE_PACK);
 			init(svc.getInputStream(), svc.getOutputStream());
 			super.doPush(monitor, refUpdates, outputStream);
 		}
@@ -1448,14 +1389,10 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 
 		protected final HttpExecuteStream execute;
 
-		protected final TransferConfig.ProtocolVersion protocolVersion;
-
 		final UnionInputStream in;
 
-		Service(String serviceName,
-				TransferConfig.ProtocolVersion protocolVersion) {
+		Service(String serviceName) {
 			this.serviceName = serviceName;
-			this.protocolVersion = protocolVersion;
 			this.requestType = "application/x-" + serviceName + "-request"; //$NON-NLS-1$ //$NON-NLS-2$
 			this.responseType = "application/x-" + serviceName + "-result"; //$NON-NLS-1$ //$NON-NLS-2$
 
@@ -1471,10 +1408,6 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 			conn.setDoOutput(true);
 			conn.setRequestProperty(HDR_CONTENT_TYPE, requestType);
 			conn.setRequestProperty(HDR_ACCEPT, responseType);
-			if (TransferConfig.ProtocolVersion.V2.equals(protocolVersion)) {
-				conn.setRequestProperty(GitProtocolConstants.PROTOCOL_HEADER,
-						GitProtocolConstants.VERSION_2_REQUEST);
-			}
 		}
 
 		void sendRequest() throws IOException {
@@ -1730,9 +1663,8 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 	class MultiRequestService extends Service {
 		boolean finalRequest;
 
-		MultiRequestService(String serviceName,
-				TransferConfig.ProtocolVersion protocolVersion) {
-			super(serviceName, protocolVersion);
+		MultiRequestService(String serviceName) {
+			super(serviceName);
 		}
 
 		/** Keep opening send-receive pairs to the given URI. */
@@ -1769,10 +1701,11 @@ public class TransportHttp extends HttpTransport implements WalkTransport,
 
 	/** Service for maintaining a single long-poll connection. */
 	class LongPollService extends Service {
-
-		LongPollService(String serviceName,
-				TransferConfig.ProtocolVersion protocolVersion) {
-			super(serviceName, protocolVersion);
+		/**
+		 * @param serviceName
+		 */
+		LongPollService(String serviceName) {
+			super(serviceName);
 		}
 
 		/** Only open one send-receive request. */
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportLocal.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportLocal.java
index 89cb65e9ac..403f98d869 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportLocal.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportLocal.java
@@ -20,7 +20,6 @@ import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.util.Collection;
 import java.util.Collections;
 import java.util.Map;
 import java.util.Set;
@@ -154,17 +153,11 @@ class TransportLocal extends Transport implements PackTransport {
 	/** {@inheritDoc} */
 	@Override
 	public FetchConnection openFetch() throws TransportException {
-		return openFetch(Collections.emptyList());
-	}
-
-	@Override
-	public FetchConnection openFetch(Collection<RefSpec> refSpecs,
-			String... additionalPatterns) throws TransportException {
 		final String up = getOptionUploadPack();
 		if (!"git-upload-pack".equals(up) //$NON-NLS-1$
-				&& !"git upload-pack".equals(up)) {//$NON-NLS-1$
-			return new ForkLocalFetchConnection(refSpecs, additionalPatterns);
-		}
+				&& !"git upload-pack".equals(up)) //$NON-NLS-1$
+			return new ForkLocalFetchConnection();
+
 		UploadPackFactory<Void> upf = (Void req,
 				Repository db) -> createUploadPack(db);
 		return new InternalFetchConnection<>(this, upf, null, openRepo());
@@ -200,23 +193,6 @@ class TransportLocal extends Transport implements PackTransport {
 	 */
 	protected Process spawn(String cmd)
 			throws TransportException {
-		return spawn(cmd, null);
-	}
-
-	/**
-	 * Spawn process
-	 *
-	 * @param cmd
-	 *            command
-	 * @param protocolVersion
-	 *            to use
-	 * @return a {@link java.lang.Process} object.
-	 * @throws org.eclipse.jgit.errors.TransportException
-	 *             if any.
-	 */
-	private Process spawn(String cmd,
-			TransferConfig.ProtocolVersion protocolVersion)
-			throws TransportException {
 		try {
 			String[] args = { "." }; //$NON-NLS-1$
 			ProcessBuilder proc = local.getFS().runInShell(cmd, args);
@@ -232,10 +208,7 @@ class TransportLocal extends Transport implements PackTransport {
 			env.remove("GIT_GRAFT_FILE"); //$NON-NLS-1$
 			env.remove("GIT_INDEX_FILE"); //$NON-NLS-1$
 			env.remove("GIT_NO_REPLACE_OBJECTS"); //$NON-NLS-1$
-			if (TransferConfig.ProtocolVersion.V2.equals(protocolVersion)) {
-				env.put(GitProtocolConstants.PROTOCOL_ENVIRONMENT_VARIABLE,
-						GitProtocolConstants.VERSION_2_REQUEST);
-			}
+
 			return proc.start();
 		} catch (IOException err) {
 			throw new TransportException(uri, err.getMessage(), err);
@@ -248,21 +221,12 @@ class TransportLocal extends Transport implements PackTransport {
 		private Thread errorReaderThread;
 
 		ForkLocalFetchConnection() throws TransportException {
-			this(Collections.emptyList());
-		}
-
-		ForkLocalFetchConnection(Collection<RefSpec> refSpecs,
-				String... additionalPatterns) throws TransportException {
 			super(TransportLocal.this);
 
 			final MessageWriter msg = new MessageWriter();
 			setMessageWriter(msg);
 
-			TransferConfig.ProtocolVersion gitProtocol = protocol;
-			if (gitProtocol == null) {
-				gitProtocol = TransferConfig.ProtocolVersion.V2;
-			}
-			uploadPack = spawn(getOptionUploadPack(), gitProtocol);
+			uploadPack = spawn(getOptionUploadPack());
 
 			final InputStream upErr = uploadPack.getErrorStream();
 			errorReaderThread = new StreamCopyThread(upErr, msg.getRawStream());
@@ -275,9 +239,7 @@ class TransportLocal extends Transport implements PackTransport {
 			upOut = new BufferedOutputStream(upOut);
 
 			init(upIn, upOut);
-			if (!readAdvertisedRefs()) {
-				lsRefs(refSpecs, additionalPatterns);
-			}
+			readAdvertisedRefs();
 		}
 
 		@Override
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
index 9eefea0c48..1242ef1b4a 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
@@ -33,7 +33,6 @@ import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SIDEBAND_AL
 import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SIDE_BAND;
 import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_SIDE_BAND_64K;
 import static org.eclipse.jgit.transport.GitProtocolConstants.OPTION_THIN_PACK;
-import static org.eclipse.jgit.transport.GitProtocolConstants.VERSION_2_REQUEST;
 import static org.eclipse.jgit.util.RefMap.toRefMap;
 
 import java.io.ByteArrayOutputStream;
@@ -710,7 +709,7 @@ public class UploadPack {
 	 * @since 5.0
 	 */
 	public void setExtraParameters(Collection<String> params) {
-		this.clientRequestedV2 = params.contains(VERSION_2_REQUEST);
+		this.clientRequestedV2 = params.contains("version=2"); //$NON-NLS-1$
 	}
 
 	/**
@@ -1195,8 +1194,7 @@ public class UploadPack {
 					new PacketLineOut(NullOutputStream.INSTANCE),
 					accumulator);
 		} else {
-			pckOut.writeString(
-					GitProtocolConstants.SECTION_ACKNOWLEDGMENTS + '\n');
+			pckOut.writeString("acknowledgments\n"); //$NON-NLS-1$
 			for (ObjectId id : req.getPeerHas()) {
 				if (walk.getObjectReader().has(id)) {
 					pckOut.writeString("ACK " + id.getName() + "\n"); //$NON-NLS-1$ //$NON-NLS-2$
@@ -1245,8 +1243,7 @@ public class UploadPack {
 			if (!pckOut.isUsingSideband()) {
 				// sendPack will write "packfile\n" for us if sideband-all is used.
 				// But sideband-all is not used, so we have to write it ourselves.
-				pckOut.writeString(
-						GitProtocolConstants.SECTION_PACKFILE + '\n');
+				pckOut.writeString("packfile\n"); //$NON-NLS-1$
 			}
 
 			accumulator.timeNegotiating = Duration
@@ -2330,8 +2327,7 @@ public class UploadPack {
 					// for us if provided a PackfileUriConfig. In this case, we
 					// are not providing a PackfileUriConfig, so we have to
 					// write this line ourselves.
-					pckOut.writeString(
-							GitProtocolConstants.SECTION_PACKFILE + '\n');
+					pckOut.writeString("packfile\n"); //$NON-NLS-1$
 				}
 			}
 			pw.writePack(pm, NullProgressMonitor.INSTANCE, packOut);