t / t4101 / diff.2-3on commit files-backend: use `die("BUG: ...")`, not `die("internal error: ...")` (04aea8d)
   1--- a/frotz
   2+++ b/frotz
   3@@ -1,2 +1,3 @@
   4 a
   5+c
   6 b
   7\ No newline at end of file