cpython

bpo-41344: Raise ValueError when creating shared memory of size 0 (GH-21556)

bpo-39994: Fix pprint handling of dict subclasses that override __repr__ (GH-21892)

Further improve accuracy of math.hypot() (GH-22013)

closes bpo-41533: Fix a potential memory leak when allocating a stack (GH-21847)

Improve asyncio-dev 'Concurrency and Multithreading' docs (GH-20882)