Update asyncio from the Tulip project

Major changes:

- StreamReader.readexactly() now raises an IncompleteReadError if the
  end of stream is reached before we received enough bytes, instead of
  returning less bytes than requested.

- Unit tests use the main asyncio module instead of submodules like events

- _UnixWritePipeTransport now also supports character devices, as
  _UnixReadPipeTransport. Patch written by Jonathan Slenders.

- Export more symbols: BaseEventLoop, BaseProactorEventLoop,
  BaseSelectorEventLoop, Queue and Queue sublasses, Empty, Full

1 files changed, 2 insertions, 0 deletions

diff --git a/Lib/asyncio/proactor_events.py b/Lib/asyncio/proactor_events.py
index ba5169e9d8..3b44f24835 100644
--- a/Lib/asyncio/proactor_events.py
+++ b/Lib/asyncio/proactor_events.py
@@ -4,6 +4,8 @@ A proactor is a "notify-on-completion" multiplexer.  Currently a
 proactor is only implemented on Windows with IOCP.
 """
 
+__all__ = ['BaseProactorEventLoop']
+
 import socket
 
 from . import base_events