diff -r d6e7ac651973 -r bb2f543b48b5 mercurial/revset.py
--- a/mercurial/revset.py	Tue Apr 14 12:53:48 2015 -0700
+++ b/mercurial/revset.py	Fri May 15 11:52:09 2015 -0500
@@ -2095,7 +2095,6 @@
     "parent": parentspec,
     "parentpost": p1,
     "only": only,
-    "onlypost": only,
 }
 
 def optimize(x, small):
@@ -2112,6 +2111,8 @@
     elif op == 'only':
         return optimize(('func', ('symbol', 'only'),
                          ('list', x[1], x[2])), small)
+    elif op == 'onlypost':
+        return optimize(('func', ('symbol', 'only'), x[1]), small)
     elif op == 'dagrangepre':
         return optimize(('func', ('symbol', 'ancestors'), x[1]), small)
     elif op == 'dagrangepost':