Assertion in Diagnostics_area::set_error_status when using a bad datetime with PS and SP

DELIMITER $$

CREATE OR REPLACE PROCEDURE p1(OUT a VARCHAR(20))

BEGIN

  SET a=10;

END;

$$

BEGIN NOT ATOMIC

  DECLARE a DATETIME;

  EXECUTE IMMEDIATE 'CALL p1(?)' USING a;

END;

$$

DELIMITER ;

DELIMITER $$

CREATE OR REPLACE PROCEDURE p1(OUT a VARCHAR(20))

BEGIN

  SET a=10;

END;

$$

BEGIN NOT ATOMIC

  DECLARE a DATETIME;

  CALL p1(a);

END;

$$

DELIMITER ;

ERROR 1292 (22007): Incorrect datetime value: '10' for column 'a' at row 1