--- a/mercurial/hg.py	Thu Aug 20 17:19:32 2015 +0200
+++ b/mercurial/hg.py	Sun Aug 30 11:47:43 2015 +0200
@@ -582,7 +582,10 @@
                     try:
                         uprev = destrepo.lookup(checkout)
                     except error.RepoLookupError:
-                        pass
+                        try:
+                            uprev = destrepo.lookup(update)
+                        except error.RepoLookupError:
+                            pass
                 if uprev is None:
                     try:
                         uprev = destrepo._bookmarks['@']