diffで「〜だけに発見」というメッセージを消す

diff -ur diff1/diffutils-2.8.1/src/diff.c diff2/diffutils-2.8.1/src/diff.c
--- diff1/diffutils-2.8.1/src/diff.c    2002-03-24 16:35:28.000000000 +0900
+++ diff2/diffutils-2.8.1/src/diff.c    2006-01-21 10:20:56.000000000 +0900
@@ -1067,7 +1067,7 @@
       char const *dir = parent->file[name0 == 0].name;

       /* See POSIX 1003.1-2001 for this format.  */
-      message ("Only in %s: %s\n", dir, name);

       /* Return EXIT_FAILURE so that diff_dirs will return
         EXIT_FAILURE ("some files differ").  */

POSIXに反しているらしいので、
http://www.opengroup.org/onlinepubs/009695399/utilities/diff.html

LANG=C diff orig new | grep -v "^Only in"　で削る方が良さそう。