Fix errors in MergeOp when using CherryPick

Commit 31050f2 adds a feature to make sure the Gerrit web UI is aware
of the cherry-picked commit used as the final patch set in a change.
However, we weren't including the submit approval on that last patch
set, which caused a NPE when merging the change.  For more discussion
of this bug see http://groups.google.com/group/repo-discuss/browse_thread/thread/975c57d88806f903

Also with 31050f2, there was another bug that would cause review scores
from all previous patch sets to show up on the final commit.  For example,
if Alice gave patch set 1 a +1 score and didn't give patch set 2 a score
at all, her +1 would show up when patch set 2 is submitted and patch set 3
is generated by Gerrit.  This bug is also now fixed.

Signed-off-by: Brad Larson <bklarson@gmail.com>
Change-Id: I492b588c31f6d81ce63e90967dfec5b823721ed4

gerrit-server/src/main/java/com/google/gerrit/server/git/MergeOp.java

@@ -800,8 +800,9 @@ public class MergeOp {
     }
 
     PatchSetApproval submitAudit = null;
+    List<PatchSetApproval> approvalList = null;
     try {
-      final List<PatchSetApproval> approvalList =
+      approvalList =
           schema.patchSetApprovals().byPatchSet(n.patchsetId).toList();
       Collections.sort(approvalList, new Comparator<PatchSetApproval>() {
         public int compare(final PatchSetApproval a, final PatchSetApproval b) {
@@ -915,10 +916,8 @@ public class MergeOp {
               }
             });
 
-    for (PatchSetApproval a : schema.patchSetApprovals().byChange(
-        n.change.getId())) {
-      // ApprovalCategory.SUBMIT is still in db but not relevant in git-store
-      if (!ApprovalCategory.SUBMIT.equals(a.getCategoryId())) {
+    if (approvalList != null) {
+      for (PatchSetApproval a : approvalList) {
         schema.patchSetApprovals().insert(
             Collections.singleton(new PatchSetApproval(ps.getId(), a)));
       }