Update HEAD in cherry-picking several commits

Without update, index is wrongly detected to be dirty
when picking the second commit.

Change-Id: Idf47ecb33e8bd38340d760806d629f67be92d2d5
Signed-off-by: Hiroshi Tomita <tomykaira@gmail.com>
Bug: 411963

org.eclipse.jgit.test/tst/org/eclipse/jgit/api/CherryPickCommandTest.java

@@ -111,6 +111,42 @@ public class CherryPickCommandTest extends RepositoryTestCase {
 		assertFalse(history.hasNext());
 	}
 
+    @Test
+    public void testSequentialCherryPick() throws IOException, JGitInternalException,
+            GitAPIException {
+        Git git = new Git(db);
+
+        writeTrashFile("a", "first line\nsec. line\nthird line\n");
+        git.add().addFilepattern("a").call();
+        RevCommit firstCommit = git.commit().setMessage("create a").call();
+
+        writeTrashFile("a", "first line\nsec. line\nthird line\nfourth line\n");
+        git.add().addFilepattern("a").call();
+        RevCommit enlargingA = git.commit().setMessage("enlarged a").call();
+
+        writeTrashFile("a",
+                "first line\nsecond line\nthird line\nfourth line\n");
+        git.add().addFilepattern("a").call();
+        RevCommit fixingA = git.commit().setMessage("fixed a").call();
+
+        git.branchCreate().setName("side").setStartPoint(firstCommit).call();
+        checkoutBranch("refs/heads/side");
+
+        writeTrashFile("b", "nothing to do with a");
+        git.add().addFilepattern("b").call();
+        git.commit().setMessage("create b").call();
+
+        CherryPickResult result = git.cherryPick().include(enlargingA).include(fixingA).call();
+        assertEquals(CherryPickResult.CherryPickStatus.OK, result.getStatus());
+
+        Iterator<RevCommit> history = git.log().call().iterator();
+        assertEquals("fixed a", history.next().getFullMessage());
+        assertEquals("enlarged a", history.next().getFullMessage());
+        assertEquals("create b", history.next().getFullMessage());
+        assertEquals("create a", history.next().getFullMessage());
+        assertFalse(history.hasNext());
+    }
+
 	@Test
 	public void testCherryPickDirtyIndex() throws Exception {
 		Git git = new Git(db);

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

@@ -122,9 +122,8 @@ public class CherryPickCommand extends GitCommand<CherryPickResult> {
 			if (headRef == null)
 				throw new NoHeadException(
 						JGitText.get().commitOnRepoWithoutHEADCurrentlyNotSupported);
-			RevCommit headCommit = revWalk.parseCommit(headRef.getObjectId());
 
-			newHead = headCommit;
+			newHead = revWalk.parseCommit(headRef.getObjectId());
 
 			// loop through all refs to be cherry-picked
 			for (Ref src : commits) {
@@ -156,12 +155,12 @@ public class CherryPickCommand extends GitCommand<CherryPickResult> {
 				merger.setBase(srcParent.getTree());
 				merger.setCommitNames(new String[] { "BASE", ourName,
 						cherryPickName });
-				if (merger.merge(headCommit, srcCommit)) {
-					if (AnyObjectId.equals(headCommit.getTree().getId(), merger
+				if (merger.merge(newHead, srcCommit)) {
+					if (AnyObjectId.equals(newHead.getTree().getId(), merger
 							.getResultTreeId()))
 						continue;
 					DirCacheCheckout dco = new DirCacheCheckout(repo,
-							headCommit.getTree(), repo.lockDirCache(),
+							newHead.getTree(), repo.lockDirCache(),
 							merger.getResultTreeId());
 					dco.setFailOnConflict(true);
 					dco.checkout();