XMLRPCResponder is used to login, which is a HTTP 1.0 server
that doesn't support reuse of connections.
It's cleaner to close connections from our side too.
This changes,
0x7fffdcf93700 CURLIO 0x7fffcd86db40 * Connection #0 to host login.agni.lindenlab.com left intact
into
0x7fffdcf93700 CURLIO 0x7fffcd8b0bd0 * Closing connection #0