add basic branch display tests
add basic branch display tests

We were not testing the output of "git branch" anywhere.
Not only does this not protect us against regressions in the
output, but we are not exercising code paths which may have
bugs (such as the one fixed by 45e2b61).

Signed-off-by: Jeff King <696e3fbcf235d40b6ea1ebd61c87cbea79d444e7@peff.net>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git