On reconnect from aiomysql (after the pool has recycled the old connection) by using ssl context it hangs forever. Interrupting gives the following Traceback:
  File "/usr/local/lib/python3.6/site-packages/aiomysql/connection.py", line 464, in _connect
    await self._request_authentication()
  File "/usr/local/lib/python3.6/site-packages/aiomysql/connection.py", line 670, in _request_authentication
    server_hostname=self._host
  File "/usr/lib/python3.6/asyncio/streams.py", line 81, in open_connection
    lambda: protocol, host, port, **kwds)
  File "/usr/lib/python3.6/asyncio/base_events.py", line 804, in create_connection
    sock, protocol_factory, ssl, server_hostname)
  File "/usr/lib/python3.6/asyncio/base_events.py", line 830, in _create_connection_transport
    yield from waiter
concurrent.futures._base.CancelledError

Probably it is related with issue30698 and issue29406.