when an xo loses connection, how long does it take to disappear from other's neighbor view?

[Morgan Collett]

Simon McVittie wrote:

> PS makes an unlimited number of connection attempts, with a short
> delay between each one (we should probably change this to use an
> exponential backoff process so the delays get longer as you're offline
> for longer, up to a maximum of perhaps 10 minutes).

#2522.