Merge 3.5 (issue #27456)

diff --cc Lib/asyncio/selector_events.py
Simple merge

diff --cc Misc/NEWS
index 8a28aad57c01189cd1ccdab68ccf0ca2b7fd62ae,73286b7eab6908bd9ad9828ec885806c89653c6a..a7e648bdcdfc9cfe217b0ef794ca67850e3966e1
--- 1/Misc/NEWS
--- 2/Misc/NEWS
+++ b/Misc/NEWS
@@@ -363,8 -254,8 +363,10 @@@ Librar
  - Issue #21201: Improves readability of multiprocessing error message.  Thanks
    to Wojciech Walczak for patch.
  
 +- asyncio: Add set_protocol / get_protocol to Transports.
 +
+ - Issue #27456: asyncio: Set TCP_NODELAY by default.
+ 
  IDLE
  ----