This PR proposes a solution to [bpo-35545](https://bugs.python.org/issue35545) by adding an optional `flowinfo` and `scopeid` to `asyncio.base_events._ipaddr_info` to carry the full address information into `_ipaddr_info` and avoid discarding IPv6 specific information.
Changelog entry & regression tests to come.
https://bugs.python.org/issue35545
*Moved from python/asyncio#493.*
This PR fixes issue python/asyncio#480, as explained in [this comment](https://github.com/python/asyncio/issues/480#issuecomment-278703828).
The `_SelectorDatagramTransport.sendto` method has to be modified ~~so `_sock.sendto` is used in all cases (because it is tricky to reliably tell if the socket is connected or not). Could that be an issue for connected sockets?~~ *EDIT* ... so `_sock.send` is used only if `_sock` is connected.
It also protects `socket.getsockname` against `OSError` in `_SelectorTransport`. This might happen on Windows if the socket is not connected (e.g. for UDP broadcasting).
https://bugs.python.org/issue31922
The waiting is pretty normal for any asyncio program, logging its time just adds
a noise to logs without any useful information provided.
https://bugs.python.org/issue34849
Various asyncio internals expect that the default executor is a
`ThreadPoolExecutor`, so deprecate passing anything else to
`loop.set_default_executor()`.
* Make ssh_handshake_timeout None by default.
* Raise ValueError if ssl_handshake_timeout is used without ssl.
* Raise ValueError if ssl_handshake_timeout is not positive.
* Convert asyncio/tasks.py to async/await
* Convert asyncio/queues.py to async/await
* Convert asyncio/test_utils.py to async/await
* Convert asyncio/base_subprocess.py to async/await
* Convert asyncio/subprocess.py to async/await
* Convert asyncio/streams.py to async/await
* Fix comments
* Convert asyncio/locks.py to async/await
* Convert asyncio.sleep to async def
* Add a comment
* Add missing news
* Convert stubs from AbstrctEventLoop to async functions
* Convert subprocess_shell/subprocess_exec
* Convert connect_read_pipe/connect_write_pip to async/await syntax
* Convert create_datagram_endpoint
* Convert create_unix_server/create_unix_connection
* Get rid of old style coroutines in unix_events.py
* Convert selector_events.py to async/await
* Convert wait_closed and create_connection
* Drop redundant line
* Convert base_events.py
* Code cleanup
* Drop redundant comments
* Fix indentation
* Add explicit tests for compatibility between old and new coroutines
* Convert windows event loop to use async/await
* Fix double awaiting of async function
* Convert asyncio/locks.py
* Improve docstring
* Convert tests to async/await
* Convert more tests
* Convert more tests
* Convert more tests
* Convert tests
* Improve test