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-blame.c

@@ -20,7 +20,7 @@
 #include "mailmap.h"
 #include "parse-options.h"
 
-static char blame_usage[] = "git-blame [options] [rev-opts] [rev] [--] file";
+static char blame_usage[] = "git blame [options] [rev-opts] [rev] [--] file";
 
 static const char *blame_opt_usage[] = {
 	blame_usage,