t7415: adjust test for dubiously-nested submodule gitdirs for v2.20.x

[git] / t / t4135 / diff-plain.diff

--- postimage.txt.orig  2010-08-18 20:13:31.432002255 -0500
+++ postimage.txt       2010-08-18 20:13:31.432002255 -0500
@@ -1 +1 @@
-preimage
+postimage