diff -r 07f1ac17b722 -r f65c6a5f256c mercurial/scmutil.py
--- a/mercurial/scmutil.py	Mon Aug 13 21:25:48 2012 +0900
+++ b/mercurial/scmutil.py	Fri Aug 31 02:06:29 2012 +0900
@@ -167,7 +167,7 @@
         # want to add "foo/bar/baz" before checking if there's a "foo/.hg"
         self.auditeddir.update(prefixes)
 
-class abstractopener(object):
+class abstractvfs(object):
     """Abstract base class; cannot be instantiated"""
 
     def __init__(self, *args, **kwargs):
@@ -219,8 +219,8 @@
     def makedirs(self, path=None, mode=None):
         return util.makedirs(self.join(path), mode)
 
-class opener(abstractopener):
-    '''Open files relative to a base directory
+class vfs(abstractvfs):
+    '''Operate files relative to a base directory
 
     This class is used to hide the details of COW semantics and
     remote file access from higher level code.
@@ -335,8 +335,10 @@
             return path.startswith('/') and path or (self.basesep + path)
         return self.base
 
-class filteropener(abstractopener):
-    '''Wrapper opener for filtering filenames with a function.'''
+opener = vfs
+
+class filtervfs(abstractvfs):
+    '''Wrapper vfs for filtering filenames with a function.'''
 
     def __init__(self, opener, filter):
         self._filter = filter
@@ -345,6 +347,8 @@
     def __call__(self, path, *args, **kwargs):
         return self._orig(self._filter(path), *args, **kwargs)
 
+filteropener = filtervfs
+
 def canonpath(root, cwd, myname, auditor=None):
     '''return the canonical path of myname, given cwd and root'''
     if util.endswithsep(root):