Rolled forward from T13102, see PHI364. An install encountered a held lock issue in a cluster which resolved itself immediately when I appeared onsite. It seemed plausible that this was because read synchronization does not put a timeout on git fetch, so if git fetch hangs for some network-related reason the lock could be held indefinitely.
See PHI466. This isn't totally concrete yet, but it looks like a user who has resigned from a revision but is still part of a package/project can continue getting notifications (just not email) in some situations; they should not.