t / t4101 / diff.2-3on commit git: treat "git -C '<path>'" as a no-op when <path> is empty (6a536e2)
   1--- a/frotz
   2+++ b/frotz
   3@@ -1,2 +1,3 @@
   4 a
   5+c
   6 b
   7\ No newline at end of file