python-BTrees fails to build with Python 3.13.0a2.

+ /usr/bin/python3 -m tox --current-env -q --recreate -e py313
/usr/lib/python3.13/site-packages/pkg_resources/__init__.py:2866: DeprecationWarning: Deprecated call to `pkg_resources.declare_namespace('zope')`.
Implementing implicit namespace packages (as specified in PEP 420) is preferred to `pkg_resources.declare_namespace`. See https://setuptools.pypa.io/en/latest/references/keywords.html#keyword-namespace-packages
  declare_namespace(pkg)
/usr/lib/python3.13/site-packages/pkg_resources/__init__.py:2866: DeprecationWarning: Deprecated call to `pkg_resources.declare_namespace('repoze')`.
Implementing implicit namespace packages (as specified in PEP 420) is preferred to `pkg_resources.declare_namespace`. See https://setuptools.pypa.io/en/latest/references/keywords.html#keyword-namespace-packages
  declare_namespace(pkg)
/usr/lib/python3.13/site-packages/pkg_resources/__init__.py:2866: DeprecationWarning: Deprecated call to `pkg_resources.declare_namespace('repoze.sphinx')`.
Implementing implicit namespace packages (as specified in PEP 420) is preferred to `pkg_resources.declare_namespace`. See https://setuptools.pypa.io/en/latest/references/keywords.html#keyword-namespace-packages
  declare_namespace(pkg)
/usr/lib/python3.13/site-packages/pkg_resources/__init__.py:2345: DeprecationWarning: Deprecated call to `pkg_resources.declare_namespace('repoze')`.
Implementing implicit namespace packages (as specified in PEP 420) is preferred to `pkg_resources.declare_namespace`. See https://setuptools.pypa.io/en/latest/references/keywords.html#keyword-namespace-packages
  declare_namespace(parent)
Running tests at level 1
Running zope.testrunner.layer.UnitTests tests:
  Set up zope.testrunner.layer.UnitTests in 0.000 seconds.
  Running:
..Traceback (most recent call last):
  File "/usr/bin/zope-testrunner", line 8, in <module>
    sys.exit(run())
             ^^^^^
  File "/usr/lib/python3.13/site-packages/zope/testrunner/__init__.py", line 31, in run
    failed = run_internal(defaults, args, script_parts=script_parts, cwd=cwd,
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/site-packages/zope/testrunner/__init__.py", line 55, in run_internal
    runner.run()
  File "/usr/lib/python3.13/site-packages/zope/testrunner/runner.py", line 191, in run
    self.run_tests()
  File "/usr/lib/python3.13/site-packages/zope/testrunner/runner.py", line 292, in run_tests
    self.ran += run_layer(self.options, layer_name, layer, tests,
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/site-packages/zope/testrunner/runner.py", line 473, in run_layer
    return run_tests(options, tests, layer_name, failures, errors, skipped,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/site-packages/zope/testrunner/runner.py", line 399, in run_tests
    test(result)
  File "/usr/lib64/python3.13/unittest/case.py", line 692, in __call__
    return self.run(*args, **kwds)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.13/unittest/case.py", line 662, in run
    result.stopTest(self)
  File "/usr/lib/python3.13/site-packages/zope/testrunner/runner.py", line 1023, in stopTest
    test.__dict__.update(self._test_state)
                         ^^^^^^^^^^^^^^^^
AttributeError: 'TestResult' object has no attribute '_test_state'
......py313: exit 1 (0.96 seconds) /builddir/build/BUILD/BTrees-5.1> zope-testrunner --test-path=src -vc pid=2189
  py313: FAIL code 1 (0.97 seconds)
  evaluation failed :( (1.02 seconds)

https://docs.python.org/3.13/whatsnew/3.13.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.13/fedora-rawhide-x86_64/06726418-python-BTrees/

For all our attempts to build python-BTrees with Python 3.13, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.13/package/python-BTrees/

Testing and mass rebuild of packages is happening in copr.
You can follow these instructions to test locally in mock if your package builds with Python 3.13:
https://copr.fedorainfracloud.org/coprs/g/python/python3.13/

Let us know here if you have any questions.

Python 3.13 is planned to be included in Fedora 41.
To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.13.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires),
so if this package is required a lot, it's important for us to get it fixed soon.

We'd appreciate help from the people who know this package best,
but if you don't want to work on this now, let us know so we can try to work around it on our side.