Fix connectivity check for new branches

If a branch did not yet exist (e.g. a new project with no commits)
Gerrit refused to allow uploading a new change for review, as the
new commit was not connected to the history.

Change-Id: Ie0beca2c51751d618655dcb739ff94de87ace75b
Signed-off-by: Shawn O. Pearce <sop@google.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/git/ReceiveCommits.java b/gerrit-server/src/main/java/com/google/gerrit/server/git/ReceiveCommits.java
index 969e98c73c..445974fe7b 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/git/ReceiveCommits.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/git/ReceiveCommits.java
@@ -763,6 +763,13 @@ public class ReceiveCommits implements PreReceiveHook, PostReceiveHook {
       walk.markStart(tip);
 
       Ref targetRef = rp.getAdvertisedRefs().get(destBranchName);
+      if (targetRef == null || targetRef.getObjectId() == null) {
+        // The destination branch does not yet exist. Assume the
+        // history being sent for review will start it and thus
+        // is "connected" to the branch.
+        return;
+      }
+
       final RevCommit h = walk.parseCommit(targetRef.getObjectId());
       h.add(SIDE_HAVE);
       walk.markStart(h);