diff -r 84fb29f5e0d2 -r eb07fbc21e9c mercurial/merge.py
--- a/mercurial/merge.py	Wed Jul 28 11:07:20 2010 +0200
+++ b/mercurial/merge.py	Tue Jul 27 23:40:46 2010 +0900
@@ -73,7 +73,7 @@
 def _checkunknown(wctx, mctx):
     "check for collisions between unknown files and files in mctx"
     for f in wctx.unknown():
-        if f in mctx and mctx[f].cmp(wctx[f].data()):
+        if f in mctx and mctx[f].cmp(wctx[f]):
             raise util.Abort(_("untracked file in working directory differs"
                                " from file in requested revision: '%s'") % f)