xdarcs-diff doesn't generate file list

An xdarcs-diff in one of my darcs working trees gives me a buffer beginning like this:

diff -rN -u old-lhc/lib/base/base.cabal new-lhc/lib/base/base.cabal
--- old-lhc/lib/base/base.cabal 2009-03-03 09:40:38.000000000 -0500
+++ new-lhc/lib/base/base.cabal 2009-03-03 09:40:42.000000000 -0500
@@ -1,6 +1,6 @@
 Cabal-version: >= 1.7
 Name: base
-Version: 1.0
+Version: 4.0
 Build-Type: Simple

 Library

But there should be a list of changed files at the beginning!