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-mailinfo.c

@@ -962,7 +962,7 @@ static int mailinfo(FILE *in, FILE *out, int ks, const char *encoding,
 }
 
 static const char mailinfo_usage[] =
-	"git-mailinfo [-k] [-u | --encoding=<encoding> | -n] msg patch <mail >info";
+	"git mailinfo [-k] [-u | --encoding=<encoding> | -n] msg patch <mail >info";
 
 int cmd_mailinfo(int argc, const char **argv, const char *prefix)
 {