Make the reliability set more consistent with the reliability list

[linkyndy]

Because one cannot blocking-pop from a list and push to a sorted set, we first push to a list (reliably), then to the set. Because of this, jobs are not lost, but a job might not end up in the sorted set, which is actually the one used when rescheduling. Hence the job will never be rescheduled. This scenario is quite extreme, but there are chances it might happen.