python-orderedset fails to build with Python 3.9.0a2.

The error:

test_orderedset (unittest.loader._FailedTest) ... ERROR

======================================================================
ERROR: test_orderedset (unittest.loader._FailedTest)
----------------------------------------------------------------------
ImportError: Failed to import test module: test_orderedset
Traceback (most recent call last):
  File "/usr/lib64/python3.9/unittest/loader.py", line 154, in loadTestsFromName
    module = __import__(module_name)
  File "/builddir/build/BUILD/orderedset-2.0.1/tests/test_orderedset.py", line 21, in <module>
    from orderedset import *
  File "/builddir/build/BUILD/orderedset-2.0.1/lib/orderedset/__init__.py", line 5, in <module>
    from ._orderedset import OrderedSet
  File "lib/orderedset/_orderedset.pyx", line 3, in init orderedset._orderedset
    from collections import Set, MutableSet, Iterable
ImportError: cannot import name Set

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.9/fedora-rawhide-x86_64/01142476-python-orderedset/

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

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.