diff -r 475552c03496 -r d7a77ad9bcce mercurial/patch.py
--- a/mercurial/patch.py	Thu May 14 13:20:40 2009 -0500
+++ b/mercurial/patch.py	Thu May 14 13:20:40 2009 -0500
@@ -1236,6 +1236,7 @@
 
     if opts.git:
         copy, diverge = copies.copies(repo, ctx1, ctx2, repo[nullid])
+        copy = copy.copy()
         for k, v in copy.items():
             copy[v] = k