project: do not update local published/ refs in dryrun mode

Bug: https://crbug.com/gerrit/13087
Change-Id: I197e6d6d07c7d325ac294b597d42e895f77c737f
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/289182
Reviewed-by: Michael Mortensen <mmortensen@google.com>
Tested-by: Mike Frysinger <vapier@google.com>

project.py

@@ -1026,10 +1026,11 @@ class Project(object):
     if GitCommand(self, cmd, bare=True).Wait() != 0:
       raise UploadError('Upload failed')
 
-    msg = "posted to %s for %s" % (branch.remote.review, dest_branch)
-    self.bare_git.UpdateRef(R_PUB + branch.name,
-                            R_HEADS + branch.name,
-                            message=msg)
+    if not dryrun:
+      msg = "posted to %s for %s" % (branch.remote.review, dest_branch)
+      self.bare_git.UpdateRef(R_PUB + branch.name,
+                              R_HEADS + branch.name,
+                              message=msg)
 
 # Sync ##
   def _ExtractArchive(self, tarpath, path=None):