CHEAP SQ: A query with inner joins and EXISTS subquery takes several times longer on MDEV-193 tree than on 5.5 main tree

SELECT MAX(al1.a) 

FROM t1 AS al1, t1 AS al2, t1 AS al3, t1 AS al4

WHERE al4.a = al3.a 

  AND (

    EXISTS ( SELECT 1 FROM t1 )

    OR al1.a > al2.a

  )

id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra

1	PRIMARY	al1	index	NULL	a	5	NULL	90	100.00	Using index

1	PRIMARY	al2	index	NULL	a	5	NULL	90	100.00	Using index; Using join buffer (flat, BNL join)

1	PRIMARY	al3	index	a	a	5	NULL	90	100.00	Using where; Using index; Using join buffer (incremental, BNL join)

1	PRIMARY	al4	ref	a	a	5	test.al3.a	10	100.00	Using index

2	SUBQUERY	t1	index	NULL	a	5	NULL	90	100.00	Using index

Warnings:

Note	1003	select max(`test`.`al1`.`a`) AS `MAX(al1.a)` from `test`.`t1` `al1` join `test`.`t1` `al2` join `test`.`t1` `al3` join `test`.`t1` `al4` where (`test`.`al4`.`a` = `test`.`al3`.`a`)

id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra

1	PRIMARY	al3	index	a	a	5	NULL	90	100.00	Using where; Using index

1	PRIMARY	al4	ref	a	a	5	test.al3.a	10	100.00	Using index

1	PRIMARY	al1	index	a	a	5	NULL	90	100.00	Using index; Using join buffer (flat, BNL join)

1	PRIMARY	al2	index	a	a	5	NULL	90	100.00	Using where; Using index; Using join buffer (incremental, BNL join)

2	SUBQUERY	t1	index	NULL	a	5	NULL	90	100.00	Using index

Warnings:

Note	1003	select max(`test`.`al1`.`a`) AS `MAX(al1.a)` from `test`.`t1` `al1` join `test`.`t1` `al2` join `test`.`t1` `al3` join `test`.`t1` `al4` where ((`test`.`al4`.`a` = `test`.`al3`.`a`) and (exists(select 1 from `test`.`t1`) or (`test`.`al1`.`a` > `test`.`al2`.`a`)))

SET optimizer_switch = 'in_to_exists=on';

CREATE TABLE t1 (a INT, KEY(a));

INSERT INTO t1 VALUES

(7),(5),(1),(204),(224),(9),(5),(0),(3);

INSERT INTO t1 SELECT al1.* FROM t1 al1, t1 al2;

SELECT MAX(al1.a) 

FROM t1 AS al1, t1 AS al2, t1 AS al3, t1 AS al4

WHERE al4.a = al3.a 

  AND (

    EXISTS ( SELECT 1 FROM t1 )

    OR al1.a > al2.a

  );