Issue1051

It is often needed to build clients/servers that support both IPv4 and IPv6.
Example:

# Echo client program
import socket
import sys

HOST = 'daring.cwi.nl'    # The remote host
PORT = 50007              # The same port as used by the server
s = None
for res in socket.getaddrinfo(HOST, PORT, socket.AF_UNSPEC,
socket.SOCK_STREAM):
    af, socktype, proto, canonname, sa = res
    try:
     s = socket.socket(af, socktype, proto)
    except socket.error, msg:
     s = None
     continue
    try:
     s.connect(sa)
    except socket.error, msg:
     s.close()
     s = None
     continue
    break

I noticed that also AI_PASSIVE is not available which is useful to build
IPv4/IPv6 independent servers.

Accepted that this is required for lookups that require both IPV4 and IPV6.

Fixing this bug will require a thorough review of the existing code, for
IPV6 compliance; a review which I will carry out soon.

These constants were added to the socket module in r4948.

More work will be necessary to support IPV6.