WeakValueDictionary when collecting from another thread.

Patch by paka.

Patch by Dhushyanth Ramasamy.

Patch by Chi Hsuan Yen.

Patch by Maciej Szulik.

Based on patch by Patrila.

Based on suggestion from Fumihiro Bessho.

setattr() must not convert combined table into split table.

Issue #28383: __hash__ documentation recommends naive XOR to combine but this
is suboptimal. Update the doc to suggest to reuse the hash() method using a
tuple, with an example.

when a GC collection happens in another thread.

Original patch and report by Armin Rigo.

Based on patch by Michael Layzell.

doesn't own its elements as limits.

Patch by Jim Fasarakis-Hilliard.

Patch by Dillon Brock.

form.

for issue #28971.

Imporoved the documentation and tests for make_archive() and unpack_archive().
Improved error handling when corresponding compress module is not available.
Brake circular dependency between shutil and tarfile modules.