Rebase: fix wrong update if original HEAD after Merge+Skip

Rebase would update the original HEAD to the wrong commit when
"skipping" the last commit after a merged commit.

Includes a test for the specific situation.

Change-Id: I087314b1834a3f11a4561f04ca5c21411d54d993
Signed-off-by: Mathias Kinzler <mathias.kinzler@sap.com>

1 files changed, 28 insertions, 16 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java
index 6629c4f8ee..70cf702ec1 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/RebaseCommand.java
@@ -218,14 +218,12 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 			if (this.operation == Operation.CONTINUE)
 				newHead = continueRebase();
 
-			List<Step> steps = loadSteps();
-
-			if (this.operation == Operation.SKIP && !steps.isEmpty())
-				checkoutCurrentHead();
+			if (this.operation == Operation.SKIP)
+				newHead = checkoutCurrentHead();
 
 			ObjectReader or = repo.newObjectReader();
-			int stepsToPop = 0;
 
+			List<Step> steps = loadSteps();
 			for (Step step : steps) {
 				if (step.action != Action.PICK)
 					continue;
@@ -250,22 +248,32 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 				if (newHead == null) {
 					return stop(commitToPick);
 				}
-				stepsToPop++;
 			}
-			if (newHead != null || steps.isEmpty()) {
+			if (newHead != null) {
 				// point the previous head (if any) to the new commit
 				String headName = readFile(rebaseDir, HEAD_NAME);
 				if (headName.startsWith(Constants.R_REFS)) {
 					RefUpdate rup = repo.updateRef(headName);
-					if (newHead != null) {
-						rup.setNewObjectId(newHead);
-						rup.forceUpdate();
+					rup.setNewObjectId(newHead);
+					Result res = rup.forceUpdate();
+					switch (res) {
+					case FAST_FORWARD:
+					case FORCED:
+					case NO_CHANGE:
+						break;
+					default:
+						throw new JGitInternalException("Updating HEAD failed");
 					}
 					rup = repo.updateRef(Constants.HEAD);
-					rup.link(headName);
-				}
-				if (this.operation == Operation.SKIP && steps.isEmpty()) {
-					checkoutCurrentHead();
+					res = rup.link(headName);
+					switch (res) {
+					case FAST_FORWARD:
+					case FORCED:
+					case NO_CHANGE:
+						break;
+					default:
+						throw new JGitInternalException("Updating HEAD failed");
+					}
 				}
 				FileUtils.delete(rebaseDir, FileUtils.RECURSIVE);
 				return new RebaseResult(Status.OK);
@@ -276,8 +284,8 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 		}
 	}
 
-	private void checkoutCurrentHead() throws IOException, NoHeadException,
-			JGitInternalException {
+	private RevCommit checkoutCurrentHead() throws IOException,
+			NoHeadException, JGitInternalException {
 		ObjectId headTree = repo.resolve(Constants.HEAD + "^{tree}");
 		if (headTree == null)
 			throw new NoHeadException(
@@ -299,6 +307,10 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 		} finally {
 			dc.unlock();
 		}
+		RevWalk rw = new RevWalk(repo);
+		RevCommit commit = rw.parseCommit(repo.resolve(Constants.HEAD));
+		rw.release();
+		return commit;
 	}
 
 	/**