
When a Worker indicates a task failed, mark it as `soft-failed` until enough workers have tried & failed at the same task. This is the first step in a blocklisting system, where tasks of an often-failing worker will be requeued to be retried by others. NOTE: currently the failure list of a task is NOT reset whenever it is requeued! This will be implemented in a future commit, and is tracked in `FEATURES.md`.