diff -r 18ac67b0814c -r 9271630f4720 mercurial/commands.py
--- a/mercurial/commands.py	Tue Oct 07 00:31:53 2014 -0700
+++ b/mercurial/commands.py	Tue Oct 07 00:38:14 2014 -0700
@@ -3381,10 +3381,12 @@
             raise util.Abort(_('no revisions specified'))
         revs = scmutil.revrange(repo, revs)
 
+    skipped = set()
     # check for merges
     for rev in repo.revs('%ld and merge()', revs):
         ui.warn(_('skipping ungraftable merge revision %s\n') % rev)
-        revs.remove(rev)
+        skipped.add(rev)
+    revs = [r for r in revs if r not in skipped]
     if not revs:
         return -1