remote: die on config error when setting URL

When invoking `git-remote --set-url` we do not check the return
value when writing the actual new URL to the configuration file,
pretending to the user that the configuration has been set while
it was in fact not persisted.

Fix this problem by dying early when setting the config fails.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/remote.c

@@ -1579,11 +1579,12 @@ static int set_url(int argc, const char **argv)
 	/* Special cases that add new entry. */
 	if ((!oldurl && !delete_mode) || add_mode) {
 		if (add_mode)
-			git_config_set_multivar(name_buf.buf, newurl,
-				"^$", 0);
+			git_config_set_multivar_or_die(name_buf.buf, newurl,
+						       "^$", 0);
 		else
-			git_config_set(name_buf.buf, newurl);
+			git_config_set_or_die(name_buf.buf, newurl);
 		strbuf_release(&name_buf);
+
 		return 0;
 	}
 
@@ -1604,9 +1605,9 @@ static int set_url(int argc, const char **argv)
 	regfree(&old_regex);
 
 	if (!delete_mode)
-		git_config_set_multivar(name_buf.buf, newurl, oldurl, 0);
+		git_config_set_multivar_or_die(name_buf.buf, newurl, oldurl, 0);
 	else
-		git_config_set_multivar(name_buf.buf, NULL, oldurl, 1);
+		git_config_set_multivar_or_die(name_buf.buf, NULL, oldurl, 1);
 	return 0;
 }
 

t/t5505-remote.sh

@@ -932,6 +932,15 @@ test_expect_success 'get-url on new remote' '
 	echo foo | get_url_test --push --all someremote
 '
 
+test_expect_success 'remote set-url with locked config' '
+	test_when_finished "rm -f .git/config.lock" &&
+	git config --get-all remote.someremote.url >expect &&
+	>.git/config.lock &&
+	test_must_fail git remote set-url someremote baz &&
+	git config --get-all remote.someremote.url >actual &&
+	cmp expect actual
+'
+
 test_expect_success 'remote set-url bar' '
 	git remote set-url someremote bar &&
 	echo bar >expect &&