A fetch result was discarded whenever the peer was no longer `Connected`
by the time the worker reported, and queued fetches were dropped silently
when the peer disconnected before the `Io::Fetch` was processed. In both
cases the fetcher's `active` entry for the repo was never cleared. Since
that entry is keyed by repo, it blocked the repository from being fetched
from any node until the process restarted.
- Report the result in `worker_result` even when the peer is no longer
connected, instead of returning early
- Report a failed fetch when an `Io::Fetch` is dropped for a disconnected
peer, so the active entry is cleared
- Flip the wire regression test to assert the entry is now cleared on
disconnect
7b910476c3