Error message on a valid recursive CTE with left join

The following test case fails with the error message {noformat} ERROR 4008 (HY000): Restrictions imposed on recursive definitions are violated for table 'ancestor_ids' {noformat} {noformat} create table folks(id int, name char(32), dob date, father int, mother int); insert into folks values (100, 'Me', '2000-01-01', 20, 30), (20, 'Dad', '1970-02-02', 10, 9), (30, 'Mom', '1975-03-03', 8, 7), (10, 'Grandpa Bill', '1940-04-05', null, null), (9, 'Grandma Ann', '1941-10-15', null, null), (25, 'Uncle Jim', '1968-11-18', 8, 7), (98, 'Sister Amy', '2001-06-20', 20, 30), (7, 'Grandma Sally', '1943-08-23', null, 6), (8, 'Grandpa Ben', '1940-10-21', null, null), (6, 'Grandgrandma Martha', '1923-05-17', null, null), (67, 'Cousin Eddie', '1992-02-28', 25, 27), (27, 'Auntie Melinda', '1971-03-29', null, null); with recursive ancestor_ids (id) as (   select father from folks where name = 'Me'   union   select mother from folks where name = 'Me'   union   select father from ancestor_ids as a left join folks on folks.id = a.id   union   select mother from ancestor_ids as a left join folks on folks.id = a.id ), ancestors as (   select p.* from folks as p, ancestor_ids as a     where p.id = a.id ) select * from ancestors; {noformat} Meanwhile the specification for CTE ancestors is quite valid as the recursive reference is in left operand of left join operation.