bpo-41568: Fix refleaks in zoneinfo subclasses (GH-21907)
* Fix refleak in C module __init_subclass__
This was leaking a reference to the weak cache dictionary for every
ZoneInfo subclass created.
* Fix refleak in ZoneInfo subclass's clear_cache
The previous version of the code accidentally cleared the global
ZONEINFO_STRONG_CACHE variable (and inducing `ZoneInfo` to create a new
strong cache) on calls to a subclass's `clear_cache()`. This would not
affect guaranteed behavior, but it's still not the right thing to do
(and it caused reference leaks).
1 file changed
