Parsed test spec with 2 sessions

starting permutation: w1_fetch w2_fetch w1_commit w2_commit
step w1_fetch: 
    SELECT payload::text
    FROM ulak.queue
    WHERE status = 'pending'
    ORDER BY id
    LIMIT 2
    FOR UPDATE SKIP LOCKED;

payload   
----------
{"seq": 1}
{"seq": 2}
(2 rows)

step w2_fetch: 
    SELECT payload::text
    FROM ulak.queue
    WHERE status = 'pending'
    ORDER BY id
    LIMIT 2
    FOR UPDATE SKIP LOCKED;

payload   
----------
{"seq": 3}
{"seq": 4}
(2 rows)

step w1_commit: COMMIT;
step w2_commit: COMMIT;