python-setuptools fails to build with Python 3.10.0a3.

spec = ModuleSpec(name='pkg_resources.extern.appdirs', loader=<pkg_resources.extern.VendorImporter object at 0x7f34d30d18e0>)

>   ???
E   ImportWarning: VendorImporter.exec_module() not found; falling back to load_module()

<frozen importlib._bootstrap>:681: ImportWarning
_______________ ERROR at setup of TestDistro.testExcludePackage ________________

self = <setuptools.tests.test_setuptools.TestDistro object at 0x7f34d15011f0>
method = <bound method TestDistro.testExcludePackage of <setuptools.tests.test_setuptools.TestDistro object at 0x7f34d15011f0>>

    def setup_method(self, method):
        self.e1 = Extension('bar.ext', ['bar.c'])
        self.e2 = Extension('c.y', ['y.c'])
    
>       self.dist = makeSetup(
            packages=['a', 'a.b', 'a.b.c', 'b', 'c'],
            py_modules=['b.d', 'x'],
            ext_modules=(self.e1, self.e2),
            package_dir={},
        )

setuptools/tests/test_setuptools.py:132: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
setuptools/tests/test_setuptools.py:29: in makeSetup
    return setuptools.setup(**args)
setuptools/__init__.py:153: in setup
    return distutils.core.setup(**attrs)
/usr/lib64/python3.10/distutils/core.py:108: in setup
    _setup_distribution = dist = klass(attrs)
setuptools/dist.py:423: in __init__
    _Distribution.__init__(self, {
/usr/lib64/python3.10/distutils/dist.py:292: in __init__
    self.finalize_options()
setuptools/dist.py:694: in finalize_options
    for ep in sorted(eps, key=by_order):
setuptools/dist.py:693: in <lambda>
    eps = map(lambda e: e.load(), pkg_resources.iter_entry_points(group))
pkg_resources/__init__.py:2447: in load
    return self.resolve()
pkg_resources/__init__.py:2453: in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
setuptools/__init__.py:16: in <module>
    import setuptools.version
setuptools/version.py:1: in <module>
    import pkg_resources
pkg_resources/__init__.py:73: in <module>
    from pkg_resources.extern import appdirs
<frozen importlib._bootstrap>:1026: in _find_and_load
    ???
<frozen importlib._bootstrap>:1005: in _find_and_load_unlocked
    ???
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

spec = ModuleSpec(name='pkg_resources.extern.appdirs', loader=<pkg_resources.extern.VendorImporter object at 0x7f34d30d18e0>)

>   ???
E   ImportWarning: VendorImporter.exec_module() not found; falling back to load_module()

<frozen importlib._bootstrap>:681: ImportWarning

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.10/fedora-rawhide-x86_64/01850805-python-setuptools/

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

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.