* Get all Nixpkgs jobs that have never built succesfully:
  select project, jobset, job from builds b1
    where project = 'nixpkgs' and jobset = 'trunk' and iscurrent = 1
    group by project, jobset, job
    having not exists
      (select 1 from builds b2 where b1.project = b2.project and b1.jobset = b2.jobset and b1.job = b2.job and finished = 1 and buildstatus = 0)
    order by project, jobset, job;