execnet emits the following warning on Python 3.10:

  File "/usr/lib64/python3.10/threading.py", line 557, in isSet
    warnings.warn('isSet() is deprecated, use is_set() instead',
DeprecationWarning: isSet() is deprecated, use is_set() instead

https://docs.python.org/3.10/whatsnew/3.10.html#deprecated

"""
The following threading methods are now deprecated:

    threading.currentThread => threading.current_thread()

    threading.activeCount => threading.active_count()

    threading.Condition.notifyAll => threading.Condition.notify_all()

    threading.Event.isSet => threading.Event.is_set()

    threading.Thread.setName => threading.Thread.name

    threading.thread.getName => threading.Thread.name

    threading.Thread.isDaemon => threading.Thread.daemon

    threading.Thread.setDaemon => threading.Thread.daemon
"""


This is just a warning, but other packages might treat it as error and fail to build, see bz1959305.

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.