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.

when a GC collection happens in another thread.

Original patch and report by Armin Rigo.

strxfrm() functions.

doesn't own its elements as limits.

doesn't own its elements as limits.

Patch by Jim Fasarakis-Hilliard.

Patch by Dillon Brock.

form.

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.