gh-159431: Handle immortal objects in _PyObject_XDecRefDelayed()

[nascheme]

Skip immortal objects both when queueing and when processing the queue, and remove the now redundant caller-side checks.

• Issue: _PyObject_XDecRefDelayed() should handle immortal objects #159431

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 CentOS9 Refleaks 3.x (tier-1) has failed when building commit b70a512.

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/#/builders/853/builds/4386) and take a look at the build logs.
4. Check if the failure is related to this commit (b70a512) 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/#/builders/853/builds/4386

Failed tests:

• test.test_multiprocessing_fork.test_processes

Failed subtests:

• test_interrupt - test.test_multiprocessing_fork.test_processes.WithProcessesTestProcess.test_interrupt

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

==

Click to see traceback logs

Traceback (most recent call last):
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/contextlib.py", line 116, in inner
    return func(*args, **kwds)
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 651, in test_interrupt
    exitcode = self._kill_process(multiprocessing.Process.interrupt)
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/contextlib.py", line 116, in inner
    return func(*args, **kwds)
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 632, in _kill_process
    self.assertEqual(join(), None)
                     ~~~~^^
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 305, in __call__
    return self.func(*args, **kwds)
           ~~~~~~~~~^^^^^^^^^^^^^^^
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/multiprocessing/process.py", line 156, in join
    res = self._popen.wait(timeout)
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 44, in wait
    return self.poll(os.WNOHANG if timeout == 0.0 else 0)
           ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 28, in poll
    pid, sts = os.waitpid(self.pid, flag)
               ~~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 628, in handler
    raise RuntimeError('join took too long: %s' % p)
RuntimeError: join took too long: <Process name='Process-2' pid=298801 parent=298798 started daemon>


Traceback (most recent call last):
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/multiprocessing/process.py", line 320, in _bootstrap
    self.run()
    ~~~~~~~~^^
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
    ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 579, in _sleep_some_event
    time.sleep(100)
    ~~~~~~~~~~^^^^^
KeyboardInterrupt
k


Traceback (most recent call last):
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/contextlib.py", line 116, in inner
    return func(*args, **kwds)
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 651, in test_interrupt
    exitcode = self._kill_process(multiprocessing.Process.interrupt)
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/contextlib.py", line 116, in inner
    return func(*args, **kwds)
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 632, in _kill_process
    self.assertEqual(join(), None)
                     ~~~~^^
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 305, in __call__
    return self.func(*args, **kwds)
           ~~~~~~~~~^^^^^^^^^^^^^^^
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/multiprocessing/process.py", line 156, in join
    res = self._popen.wait(timeout)
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 44, in wait
    return self.poll(os.WNOHANG if timeout == 0.0 else 0)
           ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/multiprocessing/popen_fork.py", line 28, in poll
    pid, sts = os.waitpid(self.pid, flag)
               ~~~~~~~~~~^^^^^^^^^^^^^^^^
  File "/var/lib/buildbot/worker/cstratak-CentOS9-x86_64/3.x.cstratak-CentOS9-x86_64.refleak/build/Lib/test/_test_multiprocessing.py", line 628, in handler
    raise RuntimeError('join took too long: %s' % p)
RuntimeError: join took too long: <Process name='Process-562' pid=192195 parent=189449 started daemon>