diff -r 07f1ac17b722 -r f65c6a5f256c mercurial/store.py
--- a/mercurial/store.py	Mon Aug 13 21:25:48 2012 +0900
+++ b/mercurial/store.py	Fri Aug 31 02:06:29 2012 +0900
@@ -418,7 +418,7 @@
             self._load()
         return iter(self.entries)
 
-class _fncacheopener(scmutil.abstractopener):
+class _fncachevfs(scmutil.abstractvfs):
     def __init__(self, op, fnc, encode):
         self.opener = op
         self.fncache = fnc
@@ -451,7 +451,7 @@
         op.createmode = self.createmode
         fnc = fncache(op)
         self.fncache = fnc
-        self.opener = _fncacheopener(op, fnc, encode)
+        self.opener = _fncachevfs(op, fnc, encode)
 
     def join(self, f):
         return self.pathsep + self.encode(f)