tolerate data arriving briefly after we hang up
tolerate data arriving briefly after we hang up

If the file receiver hangs up on an established connection, we do a
`transport.loseConnection()` on the buddy (the file sender). But apparently
it takes a moment (perhaps a roundtrip through the kernel) for the incoming
data to stop, and that used to cause an error. In May 2020 this happened 11
times in 40 days. Now we just ignore this late data.

warner/magic-wormhole-transit-relay