python-traitlets fails to build with Python 3.10.0a7.

=================================== FAILURES ===================================
________________ TestUseEnum.test_assign_scoped_enum_value_name ________________

self = <traitlets.tests.test_traitlets_enum.TestUseEnum testMethod=test_assign_scoped_enum_value_name>

    def test_assign_scoped_enum_value_name(self):
        # -- CONVERT: string => Enum value (item)
        scoped_names = ["Color.red", "Color.green", "Color.blue", "Color.yellow"]
        for value in scoped_names:
            example = self.Example()
            example.color = value
            self.assertIsInstance(example.color, Color)
>           self.assertEqual(str(example.color), value)
E           AssertionError: 'red' != 'Color.red'
E           - red
E           + Color.red

traitlets/tests/test_traitlets_enum.py:90: AssertionError

There were some changes in repr() in latest alpha of Python 3.10.
https://docs.python.org/3.10/whatsnew/changelog.html#python-3-10-0-alpha-7

bpo-40066: Enum: adjust repr() to show only enum and member name (not value, nor angle brackets) and str() to show only member name. Update and improve documentation to match.

bpo-40066: Enum’s repr() and str() have changed: repr() is now EnumClass.MemberName and str() is MemberName. Additionally, stdlib Enum’s whose contents are available as module attributes, such as RegexFlag.IGNORECASE, have their repr() as module.name, e.g. re.IGNORECASE.
https://bugs.python.org/issue40066

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.10/fedora-rawhide-x86_64/02127168-python-traitlets/

For all our attempts to build python-traitlets with Python 3.10, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.10/package/python-traitlets/

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 3.10:
https://copr.fedorainfracloud.org/coprs/g/python/python3.10/

Let us know here if you have any questions.

Python 3.10 will be included in Fedora 35. To make that update smoother, we're building Fedora packages with early pre-releases of Python 3.10.
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.