./src/package.py generate --clean fails with TypeError: 'NoneType' object is not iterable

[alex391]

[12671/12671] aws-parallelcluster ==2.11.9
simplifying edges...
Traceback (most recent call last):
  File "/usr/lib/python3.10/pdb.py", line 1723, in main
    pdb._runscript(mainpyfile)
  File "/usr/lib/python3.10/pdb.py", line 1583, in _runscript
    self.run(statement)
  File "/usr/lib/python3.10/bdb.py", line 598, in run
    exec(cmd, globals, locals)
  File "<string>", line 1, in <module>
  File "/home/alex/git/pypi-to-spack-package/src/package.py", line 1247, in <module>
    main()
  File "/home/alex/git/pypi-to-spack-package/src/package.py", line 1217, in main
    graph = _generate(queue, sqlite_cursor, args.no_new_versions)
  File "/home/alex/git/pypi-to-spack-package/src/package.py", line 778, in _generate
    spec.versions = _pkg_specifier_set_to_version_list(child, specifier, lookup)
  File "/home/alex/git/pypi-to-spack-package/src/package.py", line 494, in _pkg_specifier_set_to_version_list
    result = vn.VersionList() if not matching else _condensed_version_list(matching, all)
  File "/home/alex/git/pypi-to-spack-package/src/package.py", line 433, in _condensed_version_list
    subset = sorted(_packaging_to_spack_version(v) for v in _subset_of_versions)
  File "/home/alex/git/pypi-to-spack-package/src/package.py", line 433, in <genexpr>
    subset = sorted(_packaging_to_spack_version(v) for v in _subset_of_versions)
  File "/home/alex/git/pypi-to-spack-package/src/package.py", line 384, in _packaging_to_spack_version
    release.extend(v.release)
TypeError: 'NoneType' object is not iterable
Uncaught exception. Entering post mortem debugging
Running 'cont' or 'step' will restart the program
> /home/alex/git/pypi-to-spack-package/src/package.py(384)_packaging_to_spack_version()
-> release.extend(v.release)
(Pdb) p v
<LegacyVersion('0.14.1rc1.dev-52fb336')>
(Pdb) p v.release
None

This appears to be due to scipy's version 0.14.1rc1.dev-52fb336, which parses as a LegacyVersion rather than a Version