t4013: add tests for diff/log family output options.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/t/t4013/diff.show_initial b/t/t4013/diff.show_initial
new file mode 100644
index 0000000..4c4066a
--- /dev/null
+++ b/t/t4013/diff.show_initial
@@ -0,0 +1,7 @@
+$ git show initial
+commit 444ac553ac7612cc88969031b02b3767fb8a353a
+Author: A U Thor <author@example.com>
+Date:   Mon Jun 26 00:00:00 2006 +0000
+
+    Initial
+$