Failure on AMD64 Windows7 SP1 3.x:
https://buildbot.python.org/all/#/builders/40/builds/2053

...
test_start_unix_server_1 (test.test_asyncio.test_server.SelectorStartServerTests) ... skipped 'no Unix sockets'
test_create_connection_sock (test.test_asyncio.test_sock_lowlevel.ProactorEventLoopTests) ... ok
test_huge_content (test.test_asyncio.test_sock_lowlevel.ProactorEventLoopTests) ... ok
test_huge_content_recvinto (test.test_asyncio.test_sock_lowlevel.ProactorEventLoopTests) ... ERROR
test_sock_accept (test.test_asyncio.test_sock_lowlevel.ProactorEventLoopTests) ... C:\buildbot.python.org\3.x.kloth-win64\build\lib\test\support\__init__.py:1627: ResourceWarning: unclosed <socket.socket fd=752, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('127.0.0.1', 42975), raddr=('127.0.0.1', 42974)>
  gc.collect()
ResourceWarning: Enable tracemalloc to get the object allocation traceback
ok
test_sock_client_fail (test.test_asyncio.test_sock_lowlevel.ProactorEventLoopTests) ... ok
test_sock_client_ops (test.test_asyncio.test_sock_lowlevel.ProactorEventLoopTests) ... ok
test_unix_sock_client_ops (test.test_asyncio.test_sock_lowlevel.ProactorEventLoopTests) ... skipped 'No UNIX Sockets'
test_create_connection_sock (test.test_asyncio.test_sock_lowlevel.SelectEventLoopTests) ... ok
test_huge_content (test.test_asyncio.test_sock_lowlevel.SelectEventLoopTests) ... ok
test_huge_content_recvinto (test.test_asyncio.test_sock_lowlevel.SelectEventLoopTests) ... ok
...

======================================================================
ERROR: test_huge_content_recvinto (test.test_asyncio.test_sock_lowlevel.ProactorEventLoopTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\buildbot.python.org\3.x.kloth-win64\build\lib\asyncio\windows_events.py", line 474, in finish_recv
    return ov.getresult()
OSError: [WinError 64] The specified network name is no longer available

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\buildbot.python.org\3.x.kloth-win64\build\lib\test\test_asyncio\test_sock_lowlevel.py", line 225, in test_huge_content_recvinto
    self.loop.run_until_complete(
  File "C:\buildbot.python.org\3.x.kloth-win64\build\lib\asyncio\base_events.py", line 590, in run_until_complete
    return future.result()
  File "C:\buildbot.python.org\3.x.kloth-win64\build\lib\test\test_asyncio\test_sock_lowlevel.py", line 211, in _basetest_huge_content_recvinto
    nbytes = await self.loop.sock_recv_into(sock, buf)
  File "C:\buildbot.python.org\3.x.kloth-win64\build\lib\asyncio\proactor_events.py", line 551, in sock_recv_into
    return await self._proactor.recv_into(sock, buf)
  File "C:\buildbot.python.org\3.x.kloth-win64\build\lib\asyncio\windows_events.py", line 760, in _poll
    value = callback(transferred, key, ov)
  File "C:\buildbot.python.org\3.x.kloth-win64\build\lib\asyncio\windows_events.py", line 478, in finish_recv
    raise ConnectionResetError(*exc.args)
ConnectionResetError: [WinError 64] The specified network name is no longer available