t / t4101 / diff.1-2on commit fetch-pack: use skip_prefix() instead of starts_with() (45a3e52)
   1--- a/frotz
   2+++ b/frotz
   3@@ -1,3 +1,2 @@
   4 a
   5-b
   6-c
   7+b
   8\ No newline at end of file