Check that patch set is current before doing a rebase

If two users open a change in the WebUI and hit the 'Rebase Change' button
one after another, the rebase succeeds for the first user and a new patch
set with the rebased commit is created, but for the second user the rebase
fails because the change was modified. The bad thing is that also for the
second user a new commit and a new patch set are created, only updating
the current patch set field of the change fails in the end. By adding the
check for the current patch set in the beginning we now fail early for the
second user.

Change-Id: I52b48c695fe751d4ef8cd99e052a78dfb806a790
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/changedetail/RebaseChange.java b/gerrit-server/src/main/java/com/google/gerrit/server/changedetail/RebaseChange.java
index 9089710345..89c507bdee 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/changedetail/RebaseChange.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/changedetail/RebaseChange.java
@@ -313,6 +313,9 @@ public class RebaseChange {
       OrmException, IOException, InvalidChangeOperationException,
       PathConflictException {
     Change change = chg;
+    if (!chg.currentPatchSetId().equals(patchSetId)) {
+      throw new InvalidChangeOperationException("patch set is not current");
+    }
     final PatchSet originalPatchSet = db.patchSets().get(patchSetId);
 
     final RevCommit rebasedCommit;