store: rename field name from "opener" to "vfs" in internal classes for fncache

store: rename field name from "opener" to "vfs" in internal classes for fncache

These fields are used only in store module, so keeping "self.opener"
for backward compatibility like as "localrepository" class is not
needed.

--- a/mercurial/store.py	Tue Oct 09 01:41:55 2012 +0900
+++ b/mercurial/store.py	Tue Oct 09 01:41:55 2012 +0900
@@ -367,8 +367,8 @@
 class fncache(object):
     # the filename used to be partially encoded
     # hence the encodedir/decodedir dance
-    def __init__(self, opener):
-        self.opener = opener
+    def __init__(self, vfs):
+        self.vfs = vfs
         self.entries = None
         self._dirty = False
 
@@ -376,7 +376,7 @@
         '''fill the entries from the fncache file'''
         self._dirty = False
         try:
-            fp = self.opener('fncache', mode='rb')
+            fp = self.vfs('fncache', mode='rb')
         except IOError:
             # skip nonexistent file
             self.entries = set()
@@ -391,7 +391,7 @@
         fp.close()
 
     def _write(self, files, atomictemp):
-        fp = self.opener('fncache', mode='wb', atomictemp=atomictemp)
+        fp = self.vfs('fncache', mode='wb', atomictemp=atomictemp)
         if files:
             fp.write(encodedir('\n'.join(files) + '\n'))
         fp.close()
@@ -424,22 +424,22 @@
 
 class _fncachevfs(scmutil.abstractvfs):
     def __init__(self, vfs, fnc, encode):
-        self.opener = vfs
+        self.vfs = vfs
         self.fncache = fnc
         self.encode = encode
 
     def _getmustaudit(self):
-        return self.opener.mustaudit
+        return self.vfs.mustaudit
 
     def _setmustaudit(self, onoff):
-        self.opener.mustaudit = onoff
+        self.vfs.mustaudit = onoff
 
     mustaudit = property(_getmustaudit, _setmustaudit)
 
     def __call__(self, path, mode='r', *args, **kw):
         if mode not in ('r', 'rb') and path.startswith('data/'):
             self.fncache.add(path)
-        return self.opener(self.encode(path), mode, *args, **kw)
+        return self.vfs(self.encode(path), mode, *args, **kw)
 
 class fncachestore(basicstore):
     def __init__(self, path, vfstype, dotencode):