t / t4135 / diff-plain.diffon commit git: treat "git -C '<path>'" as a no-op when <path> is empty (6a536e2)
   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