t / t4101 / diff.2-0on commit merge-recursive: When we detect we can skip an update, actually skip it (b2c8c0a)
   1--- a/frotz
   2+++ b/frotz
   3@@ -1,2 +1,2 @@
   4 a
   5-b
   6\ No newline at end of file
   7+b