GTT: missing FUNCTION support

CREATE GLOBAL TEMPORARY TABLE gtt (c INT);

INSERT INTO gtt VALUES (1);

--delimiter //

CREATE FUNCTION f() RETURNS INT DETERMINISTIC BEGIN

  RETURN (SELECT COUNT(*) FROM gtt);

END//

--delimiter ;

SELECT f();

CURRENT_TEST: main.test2

mysqltest: At line 10: query 'SELECT f()' failed: ER_NO_SUCH_TABLE (1146): Table 'test.gtt' doesn't exist

SELECT f();

f()

1

main.test2                               [ pass ]