dbug_print(select_lex) prints inequivalent query when const table is involved

CREATE TABLE tbl_a (

  a int,

  primary key (a)

);

CREATE TABLE tbl_b (

  c int,

  d int,

  primary key (c, d)

);

INSERT INTO tbl_a VALUES (1), (2), (3);

INSERT INTO tbl_b VALUES (1, 11), (2, 22), (3, 33);

# original query

SELECT d FROM tbl_a JOIN tbl_b ON a = c WHERE a IN (1);

# dbug_print(join->select_lex) before join->optimize(), ok: prduces one row

select tbl_b.d AS d from (tbl_a join tbl_b on(tbl_a.a = tbl_b.c)) where tbl_a.a = 1;

# dbug_print(join->select_lex) before join->exec(), not equivalent: produces three rows

select tbl_b.d AS d from tbl_a join tbl_b where tbl_b.c = 1;

drop table tbl_a,tbl_b;