sIsReadable and sIsWritable return true after socket is closed.

[igloo]

First reported here: http://hackage.haskell.org/trac/ghc/ticket/2774

---

> import Network.Socket
> s <- socket AF_INET Stream 6
Loading package parsec-2.1.0.1 ... linking ... done.
Loading package network-2.2.0.1 ... linking ... done.
> bindSocket s (SockAddrInet 0 0)
> listen s 1
> sClose s
> sIsReadable s
True
> sIsWritable s
True

sIsReadable and sIsWritable return true when the SocketStatus is Connected or Listening. sClose does not change the status. Perhaps a new status Closed should be added to SocketStatus.

[bos]

This is a duplicate of ticket #6, and is already fixed.