Ok, here is a patch which is my work-in-progress subprocess_stream branch: https://codereview.appspot.com/52320045
Ignore the change on Future.set_exception, I forgot to merge with default. IMO the check_for_hangup parameter should be dropped in proactor, and _ProactorWritePipeTransportCheckForHangup should be merged into _ProactorWritePipeTransport. Still in proactor, there is a FIXME in _maybe_pause_protocol(). IMO the right fix is to include bytes of pending overlapped write in get_write_buffer_size() result. Victor
