Levels variable is never set

[foarsitter]

Looking into the uncovered lines of code (at this moment 757 out of 768 lines are covered) I noticed that the levels variable in managers.py is never being set apart from None.

According to the test-suite it can be removed safely.

Can someone review this removal?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.94%. Comparing base (6e7158b) to head (ae562b4).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #590      +/-   ##
==========================================
+ Coverage   98.56%   98.94%   +0.37%     
==========================================
  Files           6        6              
  Lines         768      760       -8     
==========================================
- Hits          757      752       -5     
+ Misses         11        8       -3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[gmcrocetti]

Hi @foarsitter.
The change looks solid.
I investigated a bit about the reasoning of those changes and the majority of it was introduced by two PRs / commits:

• 93a1a44
• https://github.com/jazzband/django-model-utils/pull/161/files

They date back to 10 years ago and it targeted Django < 2.

Also, changes look consistent with git grep levels:

All that to say LGTM, nice job.

[foarsitter]

@gmcrocetti thanks for checking out. Wasn't confided enough to merge it by my own so thanks for your approval!