Docs checks is failing with "TypeError: 'generator' object is not reversible"

[afaranha]

Pull request Make changes to allow paramiko to mostly work under FIPS #1928 is failing on Docs checks due to:

Encountered a bad command exit code!

Command: 'sphinx-build sites/docs sites/docs/_build'

Exit code: 1

Stdout:

reading sources... [ 10%] api/buffered_pipe                                     
reading sources... [ 15%] api/channel                                           

Exception occurred:
  File "/home/circleci/.pyenv/versions/3.6.15/lib/python3.6/site-packages/sphinx/util/nodes.py", line 55, in apply_source_workaround
    for classifier in reversed(node.parent.traverse(nodes.classifier)):
TypeError: 'generator' object is not reversible
The full traceback has been saved in /tmp/sphinx-err-82ovzhiy.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!

Stderr: n/a (PTYs have no stderr)


Exited with code exit status 1

as seen here

Locally this error doesn't happen and it seems to be a known issue with sphinx-doc #9809, #9810

And it would need to pin a version of "docutils" on the requirements (docutils==0.17.1)

The same issue is observed here #1925

[afaranha]

It seems the issue was fixed, as the pull request is passing now on the Docs checks.