fails:Socket::BasicSocket#recv_nonblock using IPv4 using a connected but not bound socket raises Errno::ENOTCONN
fails:Socket::BasicSocket#recv_nonblock using IPv6 using a connected but not bound socket raises Errno::ENOTCONN
fails:Socket::BasicSocket#recv_nonblock using IPv4 preserves the encoding of the given buffer
fails:Socket::BasicSocket#recv_nonblock using IPv6 preserves the encoding of the given buffer
fails(low priority excluded from JRuby 10):Socket::BasicSocket#recv_nonblock when recvfrom(2) returns 0 (if no messages are available to be received and the peer has performed an orderly shutdown) stream socket returns nil on a closed stream socket
