i18n: mark clone nonexistent repository message for translation

Mark the "repository '%s' does not exist" message added in
v1.7.4.2~21^2 (clone: die when trying to clone missing local path) by
Jeff King for translation.
Signed-off-by: NÆvar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin/clone.c

@@ -417,7 +417,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	if (path)
 		repo = xstrdup(absolute_path(repo_name));
 	else if (!strchr(repo_name, ':'))
-		die("repository '%s' does not exist", repo_name);
+		die(_("repository '%s' does not exist"), repo_name);
 	else
 		repo = repo_name;
 	is_local = path && !is_bundle;