wrong query result with jit_above_cost= 0 - Mailing list pgsql-hackers

Steps to reproduce:

CREATE TABLE emp (
    epno           NUMERIC(4),
    ename           VARCHAR(10),
    job             VARCHAR(9),
    mgr             NUMERIC(4),
    hiredate        DATE,
    sal             NUMERIC(7,2),
    comm            NUMERIC(7,2),
    deptno          NUMERIC(2)
);

INSERT INTO emp VALUES (7369,'SMITH','CLERK',7902,'17-DEC-80',800,NULL,20);
INSERT INTO emp VALUES (7499,'ALLEN','SALESMAN',7698,'20-FEB-81',1600,300,30);

set jit_above_cost= 0;

select max(epno) from emp group by rollup((deptno,epno)) order by 1 asc;