* sb/dashless:
Make usage strings dash-less
t/: Use "test_must_fail git" instead of "! git"
t/test-lib.sh: exit with small negagive int is ok with test_must_fail
Conflicts:
builtin-blame.c
builtin-mailinfo.c
builtin-mailsplit.c
builtin-shortlog.c
git-am.sh
t/t4150-am.sh
t/t4200-rerere.sh
588c038ac6