myst-nb fails to build with Python 3.14.0a6.

32 tests failed, partially with the DeprecationWarning affecting the test results, but also more. See the logs for details.

According to https://docs.python.org/dev/whatsnew/3.14.html#id3

asyncio policy system is deprecated and will be removed in Python 3.16. In particular, the following classes and functions are deprecated:
asyncio.AbstractEventLoopPolicy
asyncio.DefaultEventLoopPolicy
asyncio.WindowsSelectorEventLoopPolicy
asyncio.WindowsProactorEventLoopPolicy
asyncio.get_event_loop_policy()
asyncio.set_event_loop_policy()
asyncio.set_event_loop()
Users should use asyncio.run() or asyncio.Runner with loop_factory to use the desired event loop implementation.)


https://docs.python.org/3.14/whatsnew/3.14.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.14/fedora-rawhide-x86_64/08783307-myst-nb/

For all our attempts to build myst-nb with Python 3.14, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.14/package/myst-nb/

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 3.14:
https://copr.fedorainfracloud.org/coprs/g/python/python3.14/

Let us know here if you have any questions.

Python 3.14 is planned to be included in Fedora 43.
To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.14.
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.