`<TcpStream as Write>::poll_close` does nothing

[twittner]

It seems that <TcpStream as Write>::poll_close calls <&TcpStream as Write>::poll_close which is a no-op. Would it not be more appropriate to shutdown the write direction of the socket, i.e. call TcpStream::shutdown with std::net::Shutdown::Write? Otherwise two processes that wait on each others EOF will wait forever.

[yoshuawuyts]

@twittner what you're suggesting seems reasonable; if you have the time, a patch for this would be greatly appreciated!