python-txtorcon fails to build with Python 3.10.0rc1.

===============================================================================
[ERROR]
Traceback (most recent call last):
  File "/builddir/build/BUILD/txtorcon-20.0.0/test/test_torinfo.py", line 169, in test_attribute_access
    yield self.protocol.post_bootstrap
  File "/usr/lib/python3.10/site-packages/twisted/internet/defer.py", line 858, in _runCallbacks
    current.result = callback(  # type: ignore[misc]
  File "/builddir/build/BUILD/txtorcon-20.0.0/txtorcon/torinfo.py", line 285, in _setup_complete
    pb.callback(self)
  File "/usr/lib/python3.10/site-packages/twisted/internet/defer.py", line 661, in callback
    assert not isinstance(result, Deferred)
  File "/usr/lib64/python3.10/abc.py", line 119, in __instancecheck__
    return _abc_instancecheck(cls, instance)
  File "/builddir/build/BUILD/txtorcon-20.0.0/txtorcon/torinfo.py", line 213, in __getattribute__
    raise AttributeError(name)
builtins.AttributeError: __class__
test.test_torinfo.InfoTests.test_attribute_access
===============================================================================
[ERROR]
Traceback (most recent call last):
  File "/builddir/build/BUILD/txtorcon-20.0.0/txtorcon/torinfo.py", line 285, in _setup_complete
    pb.callback(self)
  File "/usr/lib/python3.10/site-packages/twisted/internet/defer.py", line 661, in callback
    assert not isinstance(result, Deferred)
  File "/usr/lib64/python3.10/abc.py", line 119, in __instancecheck__
    return _abc_instancecheck(cls, instance)
  File "/builddir/build/BUILD/txtorcon-20.0.0/txtorcon/torinfo.py", line 213, in __getattribute__
    raise AttributeError(name)
builtins.AttributeError: __class__
test.test_torinfo.InfoTests.test_other_bootstrap
===============================================================================
[ERROR]
Traceback (most recent call last):
Failure: twisted.internet.defer.TimeoutError: <test.test_torinfo.ProtocolIntegrationTests testMethod=test_with_arg> (test_with_arg) still running at 120.0 secs
test.test_torinfo.ProtocolIntegrationTests.test_with_arg
-------------------------------------------------------------------------------

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.10/fedora-rawhide-x86_64/02361525-python-txtorcon/

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

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 is already included in Fedora 35. To make that update smoother, we're building Fedora packages with all 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.