t / t4101 / diff.2-3on commit reset $sha1 $pathspec: require $sha1 only to be treeish (2f328c3)
   1--- a/frotz
   2+++ b/frotz
   3@@ -1,2 +1,3 @@
   4 a
   5+c
   6 b
   7\ No newline at end of file