python-async-generator fails to build with Python 3.9.0a3.

=================================== FAILURES ===================================
____ test_native_contextmanager_do_not_unchain_non_stopiteration_exceptions ____
    @pytest.mark.skipif(
        not nativeasyncgenerators,
        reason="Python < 3.6 doesn't have native async generators"
    )
    async def test_native_contextmanager_do_not_unchain_non_stopiteration_exceptions(
    ):
    
        with pytest.raises(RuntimeError) as excinfo:
            async with manager_issue29692_2():
                raise ZeroDivisionError
>       assert excinfo.value.args[0] == 'issue29692:Chained'
E       AssertionError: assert 'cannot reuse...se()/athrow()' == 'issue29692:Chained'
E         - cannot reuse already awaited aclose()/athrow()
E         + issue29692:Chained
async_generator/_tests/test_util.py:107: AssertionError

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.9/fedora-rawhide-x86_64/01198027-python-async-generator/

For all our attempts to build python-async-generator with Python 3.9, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.9/package/python-async-generator/

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 3.9:
https://copr.fedorainfracloud.org/coprs/g/python/python3.9/

Let us know here if you have any questions.

Python 3.9 will be included in Fedora 33. To make that update smoother, we're building Fedora packages with early pre-releases of Python 3.9.
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.