Copy label approvals when cherry-picking change to same branch

When a change is cherry-picked to the same branch, it does not
create a new change but creates a new patch set on the existing
change.  In this case, the labels should be copied if configured
to do so.

Bug: Issue 2652
Change-Id: I761fd1f2d7ccec9bf527cf42eb58ecab0a5db1ce

gerrit-server/src/main/java/com/google/gerrit/server/change/CherryPickChange.java

@@ -206,6 +206,7 @@ public class CherryPickChange {
       .setMessage("Uploaded patch set " + newPatchSetId.get() + ".")
       .setDraft(current.isDraft())
       .setUploader(uploader.getAccountId())
+      .setCopyLabels(true)
       .insert();
     return change.getId();
   }