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devdeps failures appear unrelated. I restarted the other jobs. 🤞

@RyanCamo , if you are okay with this fix, please approve. Thanks!

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout v5.0.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 7c3025269e1ea911019e40a60a9eb85f4e2c3218

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #14991: fix w0wz de_density_scale'

4. Push to a named branch:

git push YOURFORK v5.0.x:auto-backport-of-pr-14991-on-v5.0.x

5. Create a PR against branch v5.0.x, I would have named this PR:

"Backport PR #14991 on branch v5.0.x (fix w0wz de_density_scale)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.

@nstarman , any chance you can manually backport this to v5.0.x or is that not applicable?

Too much refactoring, making backport to v5.0.x too confusing for me. But this bug is so subtle that I think we should still try to fix up v5.0.x. @nstarman , please do a manual patch to v5.0.x. Thanks! 🙏

You are currently cherry-picking commit 7c3025269.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:

        new file:   docs/changes/cosmology/14991.bugfix.rst

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)

        deleted by us:   astropy/cosmology/flrw/tests/test_w0wzcdm.py
        deleted by us:   astropy/cosmology/flrw/w0wzcdm.py
        both modified:   astropy/cosmology/tests/test_core.py
        both modified:   astropy/cosmology/tests/test_utils.py

Will do. I have a dev branch for this, but the tests are quite different.