Issue #11647: allow contextmanager objects to be used as decorators as described in the docs. Initial patch by Ysj Ray.

interpreter is shutting down; instead, these threads are now killed when
they try to take the GIL.

Patch by Bryce Verdier.

Patch by Bryce Verdier.

to get around a mmap bug with sparse files. Patch written by Steffen Daode
Nurpmeso.

mmap bug with sparse files. Patch written by Steffen Daode Nurpmeso.

descriptor, the check of the object type doesn't read the __class__ attribute
anymore.  Fix a crash if a class override its __class__ attribute (e.g. a proxy
of the str type).

check of the object type doesn't read the __class__ attribute anymore.  Fix a
crash if a class override its __class__ attribute (e.g. a proxy of the str
type).

Patch by Lars Michelsen.