Documentation for os.environ should say that os.environ caching behavior is undefined if other threads are setting environment values

Documentation

It says here:

This mapping is captured the first time the os module is imported, typically during Python startup as part of processing site.py. Changes to the environment made after this time are not reflected in os.environ, except for changes made by modifying os.environ directly.

It should mention the caveat that such cashing would cause undefined behavior or/and crashes when other threads would be setting environment values. This would be true at least on Linux and FreeBSD.

The same should be mentioned in the documentation of the function that initializes the Python interpreter and caches environment.

These functions are not thread-safe.

Linked PRs

• gh-152979

Überprüfe die im Issue verlinkte Dokumentation zu os.environ und die Dokumentation für die Interpreter-Initialisierungsfunktion, die die Umgebung zwischenspeichert. Vergleiche den angeforderten Hinweis zur Thread-Sicherheit mit dem verlinkten PR gh-152979. Als erledigt gilt, dass beide relevanten Dokumentationsbereiche das Verhalten korrekt beschreiben, wenn andere Threads Umgebungswerte ändern.