[3.9] bpo-41735: Fix thread locks in zlib module may go wrong in rare case

[ghost]

https://bugs.python.org/issue41735

[iritkatriel]

backporting to branches other than master is automated, you don't need to create additional PRs for that.

[ghost]

backporting to branches other than master is automated, you don't need to create additional PRs for that.

There is a code conflict, a few hours ago zlib module was changed by another issue.

[iritkatriel]

What I mean is that you shouldn't have created this PR and 22132. You only needed to create PR 22126. When a core reviewer approves PR 22126 they can choose to back port the change to other branches. They have buttons that do this.

So you only make PRs against master branch. Core reviewers backport them.

[ghost]

There is a code confilct, this line was added to master branch recently:

zlibstate *state = PyType_GetModuleState(cls);

[bedevere-bot]

@ambv: Please replace # with GH- in the commit message next time. Thanks!