This should have been labeled as "DO-NOT-MERGE" until #121086 was merged. There are conflicts anyway now.

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 Ubuntu NoGIL Refleaks 3.x has failed when building commit ff5806c.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/1226/builds/2167) and take a look at the build logs.
4. Check if the failure is related to this commit (ff5806c) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/1226/builds/2167

Failed tests:

• test.test_concurrent_futures.test_thread_pool

Failed subtests:

• test_free_reference - test.test_concurrent_futures.test_thread_pool.ThreadPoolExecutorTest.test_free_reference

Summary of the results of the build (if available):

==

Traceback (most recent call last):
  File "/home/ubuntu/buildarea/3.x.itamaro-ubuntu-aws.refleak.nogil/build/Lib/test/test_concurrent_futures/executor.py", line 130, in test_free_reference
    self.assertIsNone(wr())
    ~~~~~~~~~~~~~~~~~^^^^^^
AssertionError: <test.test_concurrent_futures.executor.MyObject object at 0x20002080170> is not None


Traceback (most recent call last):
  File "/home/ubuntu/buildarea/3.x.itamaro-ubuntu-aws.refleak.nogil/build/Lib/test/test_concurrent_futures/executor.py", line 130, in test_free_reference
    self.assertIsNone(wr())
    ~~~~~~~~~~~~~~~~~^^^^^^
AssertionError: <test.test_concurrent_futures.executor.MyObject object at 0x20006090090> is not None

May I ask why this change was considered critical enough to not follow PEP 387?

It is clearly backwards incompatible and is in fact breaking code, see lark-parser/lark#1480 .