python-bleach fails to build with Python 3.9.0a2.

=================================== FAILURES ===================================
_ test_uri_value_allowed_protocols[<a href="example.com:8000">valid</a>-kwargs6-<a href="example.com:8000">valid</a>] _

data = '<a href="example.com:8000">valid</a>', kwargs = {'protocols': ['http']}
expected = '<a href="example.com:8000">valid</a>'

    @pytest.mark.parametrize('data, kwargs, expected', [
        ...,
    ])
    def test_uri_value_allowed_protocols(data, kwargs, expected):
>       assert clean(data, **kwargs) == expected
E       assert '<a>valid</a>' == '<a href="example.com:8000">valid</a>'
E         - <a>valid</a>
E         + <a href="example.com:8000">valid</a>

tests/test_clean.py:676: AssertionError
_ test_uri_value_allowed_protocols[<a href="localhost:8000">valid</a>-kwargs8-<a href="localhost:8000">valid</a>] _

data = '<a href="localhost:8000">valid</a>', kwargs = {'protocols': ['http']}
expected = '<a href="localhost:8000">valid</a>'

    @pytest.mark.parametrize('data, kwargs, expected', [
        ...,
    ])
    def test_uri_value_allowed_protocols(data, kwargs, expected):
>       assert clean(data, **kwargs) == expected
E       assert '<a>valid</a>' == '<a href="localhost:8000">valid</a>'
E         - <a>valid</a>
E         + <a href="localhost:8000">valid</a>

tests/test_clean.py:676: AssertionError
_ test_uri_value_allowed_protocols[<a href="192.168.100.100:8000">valid</a>-kwargs10-<a href="192.168.100.100:8000">valid</a>] _

data = '<a href="192.168.100.100:8000">valid</a>'
kwargs = {'protocols': ['http']}
expected = '<a href="192.168.100.100:8000">valid</a>'

    @pytest.mark.parametrize('data, kwargs, expected', [
        ...,
    ])
    def test_uri_value_allowed_protocols(data, kwargs, expected):
>       assert clean(data, **kwargs) == expected
E       assert '<a>valid</a>' == '<a href="192.168.100.100:8000">valid</a>'
E         - <a>valid</a>
E         + <a href="192.168.100.100:8000">valid</a>

tests/test_clean.py:676: AssertionError
===================== 3 failed, 308 passed in 1.36 seconds =====================

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.9/fedora-rawhide-x86_64/01140011-python-bleach/

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

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, but the initial bootstrapping has already started.
A build failure this early in the bootstrap sequence blocks us very much.