Fix merge with a normal topic

We were applying the same policy on normal topics than on crossrepo
topics.

src/main/java/com/criteo/gerrit/plugins/automerge/AutomaticMerger.java

diff --git a/src/main/java/com/criteo/gerrit/plugins/automerge/AutomaticMerger.java b/src/main/java/com/criteo/gerrit/plugins/automerge/AutomaticMerger.java
index 9bba6cc..e9779f5 100644
--- a/src/main/java/com/criteo/gerrit/plugins/automerge/AutomaticMerger.java
+++ b/src/main/java/com/criteo/gerrit/plugins/automerge/AutomaticMerger.java
@@ -153,9 +153,8 @@
 
   private void attemptToMerge(ChangeAttribute change) throws RestApiException, OrmException, NoSuchChangeException, IOException {
     final List<ChangeInfo> related = Lists.newArrayList();
-    final String topic = change.topic;
-    if (topic != null) {
-      related.addAll(api.changes().query("status: open AND topic: " + topic)
+    if (atomicityHelper.isAtomicReview(change)) {
+      related.addAll(api.changes().query("status: open AND topic: " + change.topic)
           .withOption(ListChangesOption.CURRENT_REVISION).get());
     } else {
       related.add(api.changes().id(change.id).get(EnumSet.of(ListChangesOption.CURRENT_REVISION)));