t / t4135 / diff-with quote.diffon commit diff.c: emit_diff_symbol learns DIFF_SYMBOL_REWRITE_DIFF (5af6ea9)
   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