Rebase Interoperability third part: handle stop upon conflict

There are some files that need to exist so that the CLI can continue
after the rebase has been stopped due to conflicts

Change-Id: I3cb4dc98609c059bf0cf9fd5f9e47a9c681cea2d
Signed-off-by: Mathias Kinzler <mathias.kinzler@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java

@@ -44,6 +44,7 @@ package org.eclipse.jgit.api;
 
 import java.io.BufferedReader;
 import java.io.BufferedWriter;
+import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
@@ -63,6 +64,7 @@ import org.eclipse.jgit.api.errors.JGitInternalException;
 import org.eclipse.jgit.api.errors.NoHeadException;
 import org.eclipse.jgit.api.errors.RefNotFoundException;
 import org.eclipse.jgit.api.errors.WrongRepositoryStateException;
+import org.eclipse.jgit.diff.DiffFormatter;
 import org.eclipse.jgit.dircache.DirCacheCheckout;
 import org.eclipse.jgit.lib.AbbreviatedObjectId;
 import org.eclipse.jgit.lib.Constants;
@@ -204,7 +206,7 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 						.call();
 				monitor.endTask();
 				if (newHead == null) {
-					return new RebaseResult(commitToPick);
+					return stop(commitToPick);
 				}
 				stepsToPop++;
 			}
@@ -227,6 +229,29 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 		}
 	}
 
+	private RebaseResult stop(RevCommit commitToPick) throws IOException {
+		StringBuilder sb = new StringBuilder(100);
+		sb.append("GIT_AUTHOR_NAME='");
+		sb.append(commitToPick.getAuthorIdent().getName());
+		sb.append("'\n");
+		sb.append("GIT_AUTHOR_EMAIL='");
+		sb.append(commitToPick.getAuthorIdent().getEmailAddress());
+		sb.append("'\n");
+		sb.append("GIT_AUTHOR_DATE='");
+		sb.append(commitToPick.getAuthorIdent().getWhen());
+		sb.append("'\n");
+		createFile(rebaseDir, "author-script", sb.toString());
+		createFile(rebaseDir, "message", commitToPick.getShortMessage());
+		ByteArrayOutputStream bos = new ByteArrayOutputStream();
+		DiffFormatter df = new DiffFormatter(bos);
+		df.setRepository(repo);
+		df.format(commitToPick.getParent(0), commitToPick);
+		createFile(rebaseDir, "patch", new String(bos.toByteArray(), "UTF-8"));
+		createFile(rebaseDir, "stopped-sha", repo.newObjectReader().abbreviate(
+				commitToPick).name());
+		return new RebaseResult(commitToPick);
+	}
+
 	/**
 	 * Removes the number of lines given in the parameter from the
 	 * <code>git-rebase-todo</code> file but preserves comments and other lines