--- a/mercurial/dirstate.py	Fri Dec 16 21:09:40 2011 +0900
+++ b/mercurial/dirstate.py	Fri Dec 16 21:09:40 2011 +0900
@@ -69,6 +69,7 @@
         f = {}
         for name in self._map:
             f[util.normcase(name)] = name
+        f['.'] = '.' # prevents useless util.fspath() invocation
         return f
 
     @propertycache