Parsed test spec with 3 sessions

starting permutation: s1a s2a s3a s1b s2b s3b
step s1a: SELECT * FROM queue ORDER BY id FOR UPDATE LIMIT 1;
id|data|status
--+----+------
 1|foo |NEW   
(1 row)

step s2a: SELECT * FROM queue ORDER BY id FOR UPDATE LIMIT 1; <waiting ...>
step s3a: SELECT * FROM queue ORDER BY id FOR UPDATE SKIP LOCKED LIMIT 1;
id|data|status
--+----+------
 2|bar |NEW   
(1 row)

step s1b: COMMIT;
step s2a: <... completed>
id|data|status
--+----+------
 1|foo |NEW   
(1 row)

step s2b: COMMIT;
step s3b: COMMIT;