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            
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            
step s1b: COMMIT;
step s2a: <... completed>
id             data           status         

1              foo            NEW            
step s2b: COMMIT;
step s3b: COMMIT;