python-nbconvert fails to build with Python 3.15.0b2.

______________________ TestNbConvertApp.test_help_output _______________________
self = <tests.test_nbconvertapp.TestNbConvertApp testMethod=test_help_output>
    def[39;49;00m [39;49;00mtest_help_output[39;49;00m(self[39;49;00m):[39;49;00m
        [39;49;00m"""ipython nbconvert --help-all works"""[39;49;00m[39;49;00m
>       check_help_all_output("[39;49;00mnbconvert[39;49;00m"[39;49;00m)[39;49;00m
self       = <tests.test_nbconvertapp.TestNbConvertApp testMethod=test_help_output>
tests/test_nbconvertapp.py:42: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
pkg = 'nbconvert', subcommand = None
    def[39;49;00m [39;49;00mcheck_help_all_output[39;49;00m(pkg: str[39;49;00m, subcommand: Sequence[str[39;49;00m] | None[39;49;00m = None[39;49;00m) -> tuple[39;49;00m[str[39;49;00m, str[39;49;00m]:[39;49;00m
        [39;49;00m"""test that `python -m PKG --help-all` works"""[39;49;00m[39;49;00m
        cmd = [sys.executable, "[39;49;00m-m[39;49;00m"[39;49;00m, pkg][39;49;00m
        if[39;49;00m subcommand:[39;49;00m
            cmd.extend(subcommand)[39;49;00m
        cmd.append("[39;49;00m--help-all[39;49;00m"[39;49;00m)[39;49;00m
        out, err, rc = get_output_error_code(cmd)[39;49;00m
        assert[39;49;00m rc == 0[39;49;00m, err[39;49;00m
>       assert[39;49;00m "[39;49;00mTraceback[39;49;00m"[39;49;00m not[39;49;00m in[39;49;00m err[39;49;00m
               ^^^^^^^^^^^^^^^^^^^^^^[39;49;00m
E       AssertionError
cmd        = ['/usr/bin/python3', '-m', 'nbconvert', '--help-all']
err        = 'Error in import line from /usr/lib/python3.15/site-packages/sphinxcontrib_spelling-7.3.3-py3.15-nspkg.pth: import sys..._exec_imports\n    File "<string>", line 1, in <module>\n  KeyError: "local variable \'\'sitedir\'\' is not defined"\n'
out        = 'This application is used to convert notebook files (*.ipynb) to various other\nformats.\n\nWARNING: THE COMMANDLINE I...             c.NbConvertApp.notebooks = ["my_notebook.ipynb"]\n\n            > jupyter nbconvert --config mycfg.py\n\n'
pkg        = 'nbconvert'
rc         = 0
subcommand = None

https://docs.python.org/3.15/whatsnew/3.15.html

For our attempts to build python-nbconvert with Python 3.15, see:
https://koji.fedoraproject.org/koji/search?terms=python-nbconvert&type=package&match=exact

Let us know here if you have any questions.

Python 3.15 is planned to be included in Fedora 45.
To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.15.
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.