t4013: note improvements brought by the new output code.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/t/t4013/diff.diff-tree_--pretty_--root_--summary_initial b/t/t4013/diff.diff-tree_--pretty_--root_--summary_initial
new file mode 100644
index 0000000..ea48205
--- /dev/null
+++ b/t/t4013/diff.diff-tree_--pretty_--root_--summary_initial
@@ -0,0 +1,11 @@
+$ git diff-tree --pretty --root --summary initial
+commit 444ac553ac7612cc88969031b02b3767fb8a353a
+Author: A U Thor <author@example.com>
+Date:   Mon Jun 26 00:00:00 2006 +0000
+
+    Initial
+
+ create mode 040000 dir
+ create mode 100644 file0
+ create mode 100644 file2
+$