HANDLER OPEN not rejected in stored routine when executed via PS

CREATE TABLE t1(a INT) ENGINE=InnoDB;

INSERT INTO t1 VALUES (1),(2);

DELIMITER $$

CREATE OR REPLACE PROCEDURE ph() BEGIN

  EXECUTE IMMEDIATE 'HANDLER t1 OPEN AS h';

END

$$

DELIMITER ;

CALL ph;

HANDLER h READ FIRST;

HANDLER h CLOSE;

13.1.0-dbg>CREATE TABLE t1(a INT) ENGINE=InnoDB;

Query OK, 0 rows affected (0.035 sec)

13.1.0-dbg>INSERT INTO t1 VALUES (1),(2);

Query OK, 2 rows affected (0.003 sec)

Records: 2  Duplicates: 0  Warnings: 0

13.1.0-dbg>

13.1.0-dbg>DELIMITER $$

13.1.0-dbg>CREATE OR REPLACE PROCEDURE ph() BEGIN

    ->   EXECUTE IMMEDIATE 'HANDLER t1 OPEN AS h';

    -> END

    -> $$

Query OK, 0 rows affected (0.003 sec)

13.1.0-dbg>DELIMITER ;

13.1.0-dbg>CALL ph;

Query OK, 0 rows affected (0.001 sec)

13.1.0-dbg>

13.1.0-dbg>HANDLER h READ FIRST;

+------+

| a    |

+------+

|    1 |

+------+

1 row in set (0.001 sec)

13.1.0-dbg>HANDLER h CLOSE;

Query OK, 0 rows affected (0.000 sec)

13.1.0-dbg>