t / t4101 / diff.1-3on commit mergetool: add an option for writing to a temporary directory (8f0cb41)
   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