python-citeproc-py fails to build with Python 3.10.0a5.

Traceback (most recent call last):
  File "/builddir/build/BUILD/citeproc-py-0.5.1/setup.py", line 84, in <module>
    setup(
  File "/usr/lib/python3.10/site-packages/setuptools/__init__.py", line 153, in setup
    return distutils.core.setup(**attrs)
  File "/usr/lib64/python3.10/distutils/core.py", line 148, in setup
    dist.run_commands()
  File "/usr/lib64/python3.10/distutils/dist.py", line 966, in run_commands
    self.run_command(cmd)
  File "/usr/lib64/python3.10/distutils/dist.py", line 985, in run_command
    cmd_obj.run()
  File "/usr/lib64/python3.10/distutils/command/build.py", line 135, in run
    self.run_command(cmd_name)
  File "/usr/lib64/python3.10/distutils/cmd.py", line 313, in run_command
    self.distribution.run_command(command)
  File "/usr/lib64/python3.10/distutils/dist.py", line 985, in run_command
    cmd_obj.run()
  File "/builddir/build/BUILD/citeproc-py-0.5.1/setup.py", line 74, in run
    convert_rnc()
  File "/builddir/build/BUILD/citeproc-py-0.5.1/setup.py", line 64, in convert_rnc
    import rnc2rng
  File "/usr/lib/python3.10/site-packages/rnc2rng/__init__.py", line 1, in <module>
    from . import parser, serializer
  File "/usr/lib/python3.10/site-packages/rnc2rng/parser.py", line 1, in <module>
    import rply, sys, os
  File "/usr/lib/python3.10/site-packages/rply/__init__.py", line 3, in <module>
    from rply.parsergenerator import ParserGenerator
  File "/usr/lib/python3.10/site-packages/rply/parsergenerator.py", line 12, in <module>
    from rply.grammar import Grammar
  File "/usr/lib/python3.10/site-packages/rply/grammar.py", line 2, in <module>
    from rply.utils import iteritems
  File "/usr/lib/python3.10/site-packages/rply/utils.py", line 2, in <module>
    from collections import MutableMapping
ImportError: cannot import name 'MutableMapping' from 'collections' (/usr/lib64/python3.10/collections/__init__.py)

bpo-37324: Remove deprecated aliases to Collections Abstract Base Classes
from the collections module.

https://docs.python.org/3.10/whatsnew/changelog.html#python-3-10-0-alpha-5

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.10/fedora-rawhide-x86_64/01952139-python-citeproc-py/

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

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.