t / t4135 / diff-with quote.diffon commit status: add --[no-]ahead-behind to status and commit for V2 format. (fd9b544)
   1--- "postimage".txt.orig        2010-08-18 20:13:31.744002255 -0500
   2+++ "postimage".txt     2010-08-18 20:13:31.744002255 -0500
   3@@ -1 +1 @@
   4-preimage
   5+postimage