Merge branch 'js/short-help-outside-repo-fix'

"git cmd -h" outside a repository should error out cleanly for many
commands, but instead it hit a BUG(), which has been corrected.

* js/short-help-outside-repo-fix:
  t0012: verify that built-ins handle `-h` even without gitdir
  checkout/fetch/pull/pack-objects: allow `-h` outside a repository

diff --cc builtin/checkout.c
Simple merge

diff --cc builtin/fetch.c
Simple merge

diff --cc builtin/pull.c
Simple merge