Message3521

Fix checked into trunk and release 2.2.

Jython sockets should now have identical behaviour to cpython sockets,
in this circumstance.

Strictly speaking, shutting down I/O on a server socket has no meaning,
because it is merely a connection receiving endpoint, and not a
bi-directional messaging channel, as are connected sockets.

So it should, strictly speaking, raise an exception; this would be the
standard java behaviour.

But the correct thing to do here is to do the same as cpython, i.e. let
the operation succeed.

So jython sockets will now permit shutdown of server sockets, i.e.
sockets that have 'listen'ed; the operation will silently pass, and have
no effect on the socket.