python-werkzeug fails to build with Python 3.9.0a2.

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/Werkzeug-0.14.1/docs/conf.py", line 58, in <module>
    from werkzeug import __version__ as release
  File "/builddir/build/BUILD/Werkzeug-0.14.1/docs/werkzeug/__init__.py", line 151, in <module>
    __import__('werkzeug.exceptions')
  File "/builddir/build/BUILD/Werkzeug-0.14.1/docs/werkzeug/exceptions.py", line 71, in <module>
    from werkzeug.wrappers import Response
  File "/builddir/build/BUILD/Werkzeug-0.14.1/docs/werkzeug/wrappers.py", line 27, in <module>
    from werkzeug.http import HTTP_STATUS_CODES, \
  File "/builddir/build/BUILD/Werkzeug-0.14.1/docs/werkzeug/http.py", line 1148, in <module>
    from werkzeug.datastructures import Accept, HeaderSet, ETags, Authorization, \
  File "/builddir/build/BUILD/Werkzeug-0.14.1/docs/werkzeug/datastructures.py", line 16, in <module>
    from collections import Container, Iterable, MutableSet
ImportError: cannot import name 'Container' from 'collections' (/usr/lib64/python3.9/collections/__init__.py)

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.9/fedora-rawhide-x86_64/01140226-python-werkzeug/

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

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, but the initial bootstrapping has already started.
A build failure this early in the bootstrap sequence blocks us very much.