Merge branch 'js/maint-reflog-beyond-horizon'

Merge branch 'js/maint-reflog-beyond-horizon'

* js/maint-reflog-beyond-horizon:
  t1503: fix broken test_must_fail calls
  rev-parse: tests git rev-parse --verify master@{n}, for various n
  sha1_name.c: use warning in preference to fprintf(stderr
  rev-parse: exit with non-zero status if ref@{n} is not valid.