The returned value is an instance of the `req' class. As per its
description, care should be taken to close() the request when
- done, to avoid leaking response sockets.
+ done, to avoid leaking response sockets. If end-of-file is
+ received on the socket, None is returned.
This function may either raise on OSError if an error occurs on
the socket, or a ashd.proto.protoerr if the incoming request is