dirstate: use util.normcase to build foldmap

mercurial/dirstate.py

@@ -68,7 +68,7 b' class dirstate(object):'
     def _foldmap(self):
         f = {}
         for name in self._map:
-            f[os.path.normcase(name)] = name
+            f[util.normcase(name)] = name
         return f
 
     @propertycache