t / t4135 / diff-plain.diffon commit t5405: use test_must_fail() instead of checking exit code manually (fbd6ef2)
   1--- postimage.txt.orig  2010-08-18 20:13:31.432002255 -0500
   2+++ postimage.txt       2010-08-18 20:13:31.432002255 -0500
   3@@ -1 +1 @@
   4-preimage
   5+postimage