Issue #28089: Fix a regression introduced in warnings.catch_warnings(): call
warnings.showwarning() if it was overriden inside the context manager.

Handling zero-argument super() in __init_subclass__ and
__set_name__ involved moving __class__ initialisation to
type.__new__. This requires cooperation from custom
metaclasses to ensure that the new __classcell__ entry
is passed along appropriately.

The initial implementation of that change resulted in abruptly
broken zero-argument super() support in metaclasses that didn't
adhere to the new requirements (such as Django's metaclass for
Model definitions).

The updated approach adopted here instead emits a deprecation
warning for those cases, and makes them work the same way they
did in Python 3.5.

This patch also improves the related class machinery documentation
to cover these details and to include more reader-friendly
cross-references and index entries.

names.

names.

This is still useful for single source Python 2/3 code
migrating away from inspect.getargspec(), but that wasn't
clear with the documented deprecation in place.

Issue #26273: Add new socket.TCP_CONGESTION (Linux 2.6.13) and
socket.TCP_USER_TIMEOUT (Linux 2.6.37) constants.

Patch written by Omar Sandoval.

 a descriptor that is used inside that class no longer prevents calling the
 __set_name__ method of other descriptors.

Thanks to Serhiy Storchaka for pointing out the missing notes.

Patch by Elvis Pranskevichus.

Fixes #24142: [configparser] always join multiline values to not leave the parser in an invalid state

in the documentation.

in the documentation.

Patch by Wojtek Ruszczewski.

Patch by Julien Palard.

Issue #28782: Fix a bug in the implementation ``yield from`` when checking
if the next instruction is YIELD_FROM. Regression introduced by WORDCODE
(issue #26647).

Reviewed by Serhiy Storchaka and Yury Selivanov.