Pass normalized directory names to the ignore function

This fixes a bad performance regression caused by dd0d9bd91e0a.

mercurial/dirstate.py

@@ -423,7 +423,7 b' class dirstate(object):'
                     # don't trip over symlinks
                     st = os.lstat(p)
                     if stat.S_ISDIR(st.st_mode):
-                        if not ignore(p):
+                        if not ignore(np):
                             work.append(p)
                         if imatch(np) and np in dc:
                             yield 'm', np, st