Avoid double handling of change(s) on merge of merge

A change was included twice to the batch update. This caused exception
on staging approve and changes were left on 'integrating' status.

Fixes: QTQAINFRA-3379
Change-Id: I776f942ee54351e1e9478d631a189728d5fbc658
Reviewed-by: Jukka Jokiniva <[email protected]>

Author: vs-systencess

src/main/java/com/googlesource/gerrit/plugins/qtcodereview/QtUtil.java

@@ -40,6 +40,7 @@
 import java.sql.Timestamp;
 import java.util.AbstractMap;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
@@ -512,8 +513,7 @@ public List<Map.Entry<ChangeData, RevCommit>> listChangesNotMerged(
       Repository git, final Branch.NameKey branch, final Branch.NameKey destination)
       throws IOException, BranchNotFoundException {
 
-    List<Map.Entry<ChangeData, RevCommit>> result =
-        new ArrayList<Map.Entry<ChangeData, RevCommit>>();
+    Map<Change.Id, Map.Entry<ChangeData, RevCommit>> map = new HashMap<>();
     RevWalk revWalk = new RevWalk(git);
 
     try {
@@ -542,13 +542,13 @@ public List<Map.Entry<ChangeData, RevCommit>> listChangesNotMerged(
             logger.atWarning().log(
                 "qtcodereview: commit belongs to multiple changes: %s", commit.name());
           ChangeData cd = changes.get(0);
-          result.add(new AbstractMap.SimpleEntry<ChangeData, RevCommit>(cd, commit));
+          map.put(cd.getId(), new AbstractMap.SimpleEntry<ChangeData, RevCommit>(cd, commit));
         }
       }
     } finally {
       revWalk.dispose();
     }
-    return result;
+    return new ArrayList<Map.Entry<ChangeData, RevCommit>>(map.values());
   }
 
   public static RevCommit merge(

src/test/java/com/googlesource/gerrit/plugins/qtcodereview/QtCommandBuildApproveIT.java

@@ -130,6 +130,39 @@ public void cherryPicked_Stays_Intact_After_Merge_And_Build() throws Exception {
     assertThat(changes.id(project.get(), "master", cp.changeId).get(CURRENT_REVISION).status).isEqualTo(ChangeStatus.NEW);
   }
 
+  @Test
+  public void avoid_Double_Handling_Of_Change_On_Merge_Of_Merge() throws Exception {
+    // make a change on feature branch
+    final PushOneCommit.Result f1 = pushCommit("feature", "f1-commitmsg", "f1-file", "f1-content");
+    approve(f1.getChangeId());
+    gApi.changes().id(f1.getCommit().getName()).current().submit();
+
+    // make a change on master branch
+    final PushOneCommit.Result m1 = pushCommit("master", "m1-commitmsg", "m1-file", "m1-content");
+    approve(m1.getChangeId());
+
+    // merge feature branch into master
+    final PushOneCommit mm = pushFactory.create(admin.newIdent(), testRepo);
+    mm.setParents(ImmutableList.of(f1.getCommit(), m1.getCommit()));
+    final PushOneCommit.Result m = mm.to("refs/for/master");
+    m.assertOkStatus();
+    approve(m.getChangeId());
+
+    // Stage master branch change
+    QtStage(m1);
+    // Stage merge change
+    QtStage(m);
+
+    // Create build and approve it
+    QtNewBuild("master", "merge-build-000");
+    QtApproveBuild("master", "merge-build-000");
+
+    final Changes changes = gApi.changes();
+    assertThat(changes.id(project.get(), "feature", f1.getChangeId()).get(CURRENT_REVISION).status).isEqualTo(ChangeStatus.MERGED);
+    assertThat(changes.id(project.get(), "master", m1.getChangeId()).get(CURRENT_REVISION).status).isEqualTo(ChangeStatus.MERGED);
+    assertThat(changes.id(project.get(), "master", m.getChangeId()).get(CURRENT_REVISION).status).isEqualTo(ChangeStatus.MERGED);
+  }
+
   @Test
   public void multiChange_New_Staged_Integrating_Failed() throws Exception {
     // Push 3 independent commits