ReceiveCommits: Parse body before accessing full commit message

Change-Id: I49e57e82e8d7de941a0e2e6a827cda1a2aa303eb

java/com/google/gerrit/server/git/receive/ReceiveCommits.java

diff --git a/java/com/google/gerrit/server/git/receive/ReceiveCommits.java b/java/com/google/gerrit/server/git/receive/ReceiveCommits.java
index 20dc84a..3e1643a 100644
--- a/java/com/google/gerrit/server/git/receive/ReceiveCommits.java
+++ b/java/com/google/gerrit/server/git/receive/ReceiveCommits.java
@@ -2712,10 +2712,13 @@
 
     /** prints a warning if the new PS has the same tree as the previous commit. */
     private void sameTreeWarning() throws IOException {
-      RevCommit newCommit = receivePack.getRevWalk().parseCommit(newCommitId);
+      RevWalk rw = receivePack.getRevWalk();
+      RevCommit newCommit = rw.parseCommit(newCommitId);
       RevCommit priorCommit = revisions.inverse().get(priorPatchSet);
 
       if (newCommit.getTree().equals(priorCommit.getTree())) {
+        rw.parseBody(newCommit);
+        rw.parseBody(priorCommit);
         boolean messageEq =
             Objects.equals(newCommit.getFullMessage(), priorCommit.getFullMessage());
         boolean parentsEq = parentsEqual(newCommit, priorCommit);