--- a/mercurial/exchange.py	Mon Aug 18 20:23:37 2014 -0400
+++ b/mercurial/exchange.py	Fri Aug 15 19:18:21 2014 -0700
@@ -373,7 +373,6 @@
         return
     pushop.stepsdone.add('changesets')
     # Send known heads to the server for race detection.
-    pushop.stepsdone.add('changesets')
     if not _pushcheckoutgoing(pushop):
         return
     pushop.repo.prepushoutgoinghooks(pushop.repo,