t / t4101 / diff.1-3on commit add reentrant variants of sha1_to_hex and find_unique_abbrev (af49c6d)
   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