git-commit: only append a newline to -m mesg if necessary

Currently, git will append two newlines to every message supplied via
the -m switch.  The purpose of this is to allow -m to be supplied
multiple times and have each supplied string become a paragraph in the
resulting commit message.

Normally, this does not cause a problem since any trailing newlines will
be removed by the cleanup operation.  If cleanup=verbatim for example,
then the trailing newlines will not be removed and will survive into the
resulting commit message.

Instead, let's ensure that the string supplied to -m is newline terminated,
but only append a second newline when appending additional messages.

Fixes the test in t7502.

Signed-off-by: Brandon Casey <drafnel@gmail.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/commit.c

@@ -124,8 +124,10 @@ static int opt_parse_m(const struct option *opt, const char *arg, int unset)
 	if (unset)
 		strbuf_setlen(buf, 0);
 	else {
+		if (buf->len)
+			strbuf_addch(buf, '\n');
 		strbuf_addstr(buf, arg);
-		strbuf_addstr(buf, "\n\n");
+		strbuf_complete_line(buf);
 	}
 	return 0;
 }

t/t7502-commit.sh

@@ -204,7 +204,7 @@ test_expect_success 'cleanup commit messages (verbatim option,-F)' '
 
 '
 
-test_expect_failure 'cleanup commit messages (verbatim option,-m)' '
+test_expect_success 'cleanup commit messages (verbatim option,-m)' '
 
 	echo >>negative &&
 	git commit --cleanup=verbatim -m "$mesg_with_comment_and_newlines" -a &&