diff -r d6453f6fbdba -r 2f34746c27df mercurial/revset.py
--- a/mercurial/revset.py	Tue Apr 14 16:23:54 2015 -0400
+++ b/mercurial/revset.py	Fri May 15 22:38:24 2015 +0900
@@ -2094,7 +2094,6 @@
     "ancestor": ancestorspec,
     "parent": parentspec,
     "parentpost": p1,
-    "only": only,
 }
 
 def optimize(x, small):