Doing a socket/listen on an unspecified address with an unspecified
address family is likely to result in an AF_INET6 socket on an IPv6
capable system, which under OpenBSD means IPv6 only - not IPv4 *and*
IPv6. In this case trying to connect to this socket from an IPv4
loopback address is not going to end well.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4807057