diff -r 81fc9678b018 -r 65f4512e40e4 mercurial/commands.py
--- a/mercurial/commands.py	Thu Jun 09 01:19:39 2011 +0800
+++ b/mercurial/commands.py	Sat Jun 11 14:14:11 2011 +0200
@@ -3106,7 +3106,7 @@
             if opts.get('exact') or opts.get('import_branch'):
                 repo.dirstate.setbranch(branch or 'default')
 
-            files = {}
+            files = set()
             patch.patch(ui, repo, tmpname, strip=strip, files=files,
                         eolmode=None, similarity=sim / 100.0)
             files = list(files)