Reindex a change that during MergeOp is found to be already merged

If in MergeOp we find that a change to be merged is actually already
merged its status is simply set to MERGED. After updating the change
status the change should be reindexed.

Change-Id: Ib5bb4e1fc9b60e10640add32a859210e10189201
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

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

@@ -509,6 +509,7 @@ public class MergeOp {
             commit.statusCode = CommitMergeStatus.ALREADY_MERGED;
             try {
               setMerged(chg, null);
+              indexer.index(chg);
             } catch (OrmException e) {
               log.error("Cannot mark change " + chg.getId() + " merged", e);
             }