Issue #20311: Revert 033137c12d88, select.epoll.poll() rounds again the timeout
towards zero
(Merge 3.3) Issue #20311: Revert 033137c12d88 (02f9db3e684e),
select.epoll.poll() rounds again the timeout towards zero
Issue #20311: Revert e042ea77a152 and 7ce7295393c2, PollSelector.select() and
EpollSelector.select() round again the timeout towards zero
Issue #20311: selectors: Add a resolution attribute to BaseSelector.
Issue #20311: asyncio: Add a granularity attribute to BaseEventLoop: maximum
between the resolution of the BaseEventLoop.time() method and the resolution of
the selector. The granuarility is used in the scheduler to round time and
deadline.
test_selectors: remove unused imports
Fix asyncio tests: define resolution
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
#20348: fix headers markup in Argument Clinic howto.  Patch by Moritz Neeb.
Issue #20331: Fixed possible FD leaks in various modules:
http.server, imghdr, mailcap, mimetypes, xml.etree.
Issue #20331: Fixed possible FD leaks in various modules:
http.server, imghdr, mailcap, mimetypes, xml.etree.
linkify
update sphinx url
merge 3.3
asyncio: Don't export BaseEventLoop, BaseSelectorEventLoop nor
BaseProactorEventLoop

Import them from submodules if you really need them.
Issue 19944: Fix importlib.find_spec() so it imports parents as needed.

The function is also moved to importlib.util.
Issue #20311: Fix test_telnetlib, set the resolution of the MockSelector
Merge latest Tulip into asyncio

- Make the new granularity attribute private
- Simplify BaseEventLoop._run_once(): avoid math.ceil(), use simple arithmetic
  instead
asyncio: Fix race in FastChildWatcher (by its original author, Anthony Baire).
asyncio: Locks refactor: use a separate context manager; remove Semaphore._locked.