t4013 diff format tests update

This changes one test commit in the sequence to have more than
one lines of commit log.  A few output formats (--pretty=email
aka format-patch and --pretty=oneline) need to behave
differently on single and multi-line log, and this change will
help catching breakages.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/t/t4013/diff.whatchanged_--patch-with-stat_master_--_dir_ b/t/t4013/diff.whatchanged_--patch-with-stat_master_--_dir_
index b6d9752..13789f1 100644
--- a/t/t4013/diff.whatchanged_--patch-with-stat_master_--_dir_
+++ b/t/t4013/diff.whatchanged_--patch-with-stat_master_--_dir_
@@ -18,7 +18,7 @@
 +1
 +2
 
-commit 889b315013ef9f2e2f90aa0b054b267c8a557847
+commit 9a6d4949b6b76956d9d5e26f2791ec2ceff5fdc0
 Author: A U Thor <author@example.com>
 Date:   Mon Jun 26 00:02:00 2006 +0000
 
@@ -38,11 +38,13 @@
 +E
 +F
 
-commit 7952a93e09bf565b5592766a438b40cd81f4846f
+commit 1bde4ae5f36c8d9abe3a0fce0c6aab3c4a12fe44
 Author: A U Thor <author@example.com>
 Date:   Mon Jun 26 00:01:00 2006 +0000
 
     Second
+    
+    This is the second commit.
 ---
  dir/sub |    2 ++
  1 files changed, 2 insertions(+), 0 deletions(-)