python-patsy fails to build with Python 3.9.0a2.

Running Sphinx v2.2.2
...
Configuration error:
There is a programmable error in your configuration file:
Traceback (most recent call last):
  File "/usr/lib/python3.9/site-packages/sphinx/config.py", line 361, in eval_config_file
    execfile_(filename, namespace)
  File "/usr/lib/python3.9/site-packages/sphinx/util/pycompat.py", line 81, in execfile_
    exec(code, _globals)
  File "/builddir/build/BUILD/patsy-0.5.1/doc/conf.py", line 33, in <module>
    import patsy
  File "/builddir/build/BUILD/patsy-0.5.1/doc/../patsy/__init__.py", line 77, in <module>
    import patsy.highlevel
  File "/builddir/build/BUILD/patsy-0.5.1/doc/../patsy/highlevel.py", line 19, in <module>
    from patsy.design_info import DesignMatrix, DesignInfo
  File "/builddir/build/BUILD/patsy-0.5.1/doc/../patsy/design_info.py", line 36, in <module>
    from patsy.constraint import linear_constraint
  File "/builddir/build/BUILD/patsy-0.5.1/doc/../patsy/constraint.py", line 13, in <module>
    from collections import Mapping
ImportError: cannot import name 'Mapping' from 'collections' (/usr/lib64/python3.9/collections/__init__.py)

See https://docs.python.org/3.9/whatsnew/3.9.html#removed

"The abstract base classes in collections.abc no longer are exposed in the regular collections module. This will help create a clearer distinction between the concrete classes and the abstract base classes."


For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.9/fedora-rawhide-x86_64/01173165-python-patsy/

For all our attempts to build python-patsy with Python 3.9, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.9/package/python-patsy/

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 3.9:
https://copr.fedorainfracloud.org/coprs/g/python/python3.9/

Let us know here if you have any questions.

Python 3.9 will be included in Fedora 33. To make that update smoother, we're building Fedora packages with early pre-releases of Python 3.9.
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.