Two connections to the same peer race whenever both sides dial at once:
we open one to send a browse, the peer opens one to deliver a search
reply. The registry keeps one actor per username, and until now stopped
the older one on the spot, which closed the socket carrying our browse
before the listing could arrive. Under load the stress gate lost up to
two thirds of its browses that way.
A replaced actor is now retired instead: it sends nothing new, keeps
reading for thirty seconds so a reply already on the wire still reaches
the client, and then stops itself. The peer closing a retired connection
is expected and reported as a clean close, so it cannot fail transfers
running on the connection that took over.
Michel de Graaf
ea168605b5