--- a/tests/test-hgk.t	Tue Nov 18 17:36:24 2014 -0800
+++ b/tests/test-hgk.t	Tue Nov 18 21:38:19 2014 -0800
@@ -16,5 +16,32 @@
   phase draft
   
   adda
+  $ echo b > b
+  $ hg ci -Am addb
+  adding b
+  $ hg log -T '{node}\n'
+  102a90ea7b4a3361e4082ed620918c261189a36a
+  07f4944404050f47db2e5c5071e0e84e7a27bba9
+
+  $ hg debug-diff-tree 07f494440405 102a90ea7b4a
+  :000000 100664 000000000000 1e88685f5dde N	b	b
+  $ hg debug-diff-tree 07f494440405 102a90ea7b4a --patch
+  diff --git a/b b/b
+  new file mode 100644
+  --- /dev/null
+  +++ b/b
+  @@ -0,0 +1,1 @@
+  +b
+
+Ensure that diff-tree output isn't affected by diffopts
+  $ hg --config diff.noprefix=True debug-diff-tree 07f494440405 102a90ea7b4a
+  :000000 100664 000000000000 1e88685f5dde N	b	b
+  $ hg --config diff.noprefix=True debug-diff-tree --patch 07f494440405 102a90ea7b4a
+  diff --git a/b b/b
+  new file mode 100644
+  --- /dev/null
+  +++ b/b
+  @@ -0,0 +1,1 @@
+  +b
 
   $ cd ..