t / t4101 / diff.0-2on commit fsck.c:fsck_commit(): use skip_prefix() to verify and skip constant (2d820a6)
   1--- a/frotz
   2+++ b/frotz
   3@@ -1,2 +1,2 @@
   4 a
   5-b
   6+b
   7\ No newline at end of file