(Based on a patch from Renee Chu.)

Closes #21801.

raises an exception if there is no current loop

Patch from Yayoi Ukai.

From the combined efforts of Berber Peksage, Andrew Svetlov, and Yayoi Ukai.

event loop is running. You must first stop the event loop and then wait until
it stopped, before closing it.

enables debug mode of the event loop.

environment variable is set

exception if the current loop is not None.

Guido van Rossum wrote:

"The behavior that you can set the loop to None (and keep track of it
explicitly) is part of the spec, and this should still be supported even in
debug mode. The behavior that we raise an error if you are caught having
multiple active loops per thread is just a debugging heuristic, and it
shouldn't break code that follows the spec."

Patch by Olive Kilburn.

Add note to demohelp.txt about doing so.

to be executed.

available bytes from the "self pipe", not only a single byte. This change
reduces the risk of having the pipe full and so getting the innocuous
"BlockingIOError: [Errno 11] Resource temporarily unavailable" message.

bytes or character strings

Issue #21722: The distutils "upload" command now exits with a non-zero return code when uploading fails.
Patch by Martin Dengler.

- Add a missing import
- Remove an unused import
- Remove unused variables

calls to time.monotonic(). Use a "fast select" and a "slow select" instead.

Python 3.5

- Drop __slots__ optimization of CoroWrapper to be able to set the __qualname__
  attribute.
- Add tests on __name__, __qualname__ and __module__ of a coroutine function
  and coroutine object.
- Fix test_tasks when run in debug mode (PYTHONASYNCIODEBUG env var set) on
  Python 3.3 or 3.4

maximum size. Patch written by Vajrasky Kok.