diff -r 003d1f174fe1 -r e5eedd74e70f mercurial/commands.py
--- a/mercurial/commands.py	Thu Nov 01 12:05:14 2007 +0100
+++ b/mercurial/commands.py	Thu Nov 01 12:17:59 2007 -0700
@@ -873,7 +873,8 @@
     a = "1\n2\n3\n4\n"
     b = "1\n2\n3\ninsert\n4\n"
     fa = writetemp(a)
-    d = mdiff.unidiff(a, None, b, None, os.path.basename(fa))
+    d = mdiff.unidiff(a, None, b, None, os.path.basename(fa),
+        os.path.basename(fa))
     fd = writetemp(d)
 
     files = {}