diff -r a9b427b5821e -r e0a0af140f2e mercurial/context.py
--- a/mercurial/context.py	Sun May 09 19:11:02 2010 +0200
+++ b/mercurial/context.py	Tue May 11 20:13:52 2010 +0200
@@ -685,7 +685,7 @@
         def findflag(ctx):
             mnode = ctx.changeset()[0]
             node, flag = self._repo.manifest.find(mnode, orig)
-            ff = self._repo.dirstate.flagfunc(lambda x: flag or None)
+            ff = self._repo.dirstate.flagfunc(lambda x: flag or '')
             try:
                 return ff(path)
             except OSError: