should not serve old v2 statuses
when a v2 directory goes away, other tor authorities keep serving their cached copy of the v2 status document of that directory.
If that status directory is old this will result in clients (clients or other relays?) downloading the status document, realizing it's to old, and trying to download it again. ad inf.
While tor26 was serving dizum's two-day old status document it was completely swamped. it had thousands of directory requests open at a time, they were consuming all the bandwidth and memory and it didn't even get to properly participate in consensus building.
Removing dizum's old status document from the cache and restarting tor26 made it happy. It now says 404 and clients don't come back (or if they do, at least it's a cheap 404 and not "here's 100k you'll throw away immediately, have it as often as you want".
I think we should stop serving expired status documents.
Or maybe we should stop serving them entirely. If we still need them between authorities, let's move them to a different URL.