t / t4101 / diff.1-3on commit $GIT_COMMON_DIR: a new environment variable (c7b3a3d)
   1--- a/frotz
   2+++ b/frotz
   3@@ -1,3 +1,3 @@
   4 a
   5-b
   6 c
   7+b
   8\ No newline at end of file