Merge branch 'sb/dashless'

* 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

builtin-mailsplit.c

@@ -9,7 +9,7 @@
 #include "path-list.h"
 
 static const char git_mailsplit_usage[] =
-"git-mailsplit [-d<prec>] [-f<n>] [-b] -o<directory> [<mbox>|<Maildir>...]";
+"git mailsplit [-d<prec>] [-f<n>] [-b] -o<directory> [<mbox>|<Maildir>...]";
 
 static int is_from_line(const char *line, int len)
 {