#1619 server_epoll, net.adns: Empty UDP packet sent on connect
net.adns wraps the DNS socket with an API that ends up making it watch for both read and write(able) events. With server_select, the send method is disabled by net.adns, but this does not work the same way in server_epoll and it ends up trying to send the empty write buffer. With TCP this does nothing but is needed for LuaSec sometimes(?), but with UDP DNS it ends up sending an empty packet.