Don't add "This patchset was cherry picked to ..." for the same change

If a patchset is cherry-picked to the same destination branch and
ends up on the same change, it does not make sense to add the "This
patchset was cherry picked to change ..." message.

An example of when this can happen is when the user has a series of
dependent changes under review, i.e.:

  Change 3
  Change 2
  Change 1
  HEAD of master branch

where "Change 3" has been code reviewed and accepted, but cannot be
submitted because the preceding changes are still under review.

The user wants to rebase Change 3 so it does not depend on 1 and 2,
but instead of doing an interactive rebase locally and uploading a new
patchset, uses the cherry-pick button to cherry-pick the latest patchset
of Change 3 onto the HEAD of master.  This results in a new patchset
being created on the same change, which no longer has dependency on
Change 2.

In this case, it makes more sense for the message to say "Uploaded
patch set N" instead of "This patchset was cherry picked to ... ".

Change-Id: Ib512244073285005eb230f2a1ba372e427afd8fd

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

diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/change/CherryPickChange.java b/gerrit-server/src/main/java/com/google/gerrit/server/change/CherryPickChange.java
index 2c20b03..1e748d9 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/change/CherryPickChange.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/change/CherryPickChange.java
@@ -193,10 +193,12 @@
       PatchSet.Id patchSetId, RevCommit cherryPickCommit,
       RefControl refControl) throws InvalidChangeOperationException,
       IOException, OrmException, NoSuchChangeException {
-    patchSetInserterFactory
-        .create(git, revWalk, refControl, currentUser, change, cherryPickCommit)
-        .setMessage(buildChangeMessage(patchSetId, change))
-        .insert();
+    final PatchSetInserter inserter = patchSetInserterFactory
+        .create(git, revWalk, refControl, currentUser, change, cherryPickCommit);
+    final PatchSet.Id newPatchSetId = inserter.getPatchSetId();
+    inserter
+      .setMessage("Uploaded patch set " + newPatchSetId.get() + ".")
+      .insert();
     return change.getId();
   }