t / t4101 / diff.2-1on commit grep: move sha1-reading mutex into low-level code (b3aeb28)
   1--- a/frotz
   2+++ b/frotz
   3@@ -1,2 +1,3 @@
   4 a
   5-b
   6\ No newline at end of file
   7+b
   8+c