Speed up equal_degree_factors in even characteristic.

[bwesterb]

Summary

Speeds up equal_degree_factors in even characteristic.

Type

• Fix (bug / correctness)
• Feature (new capability)
• Performance
• Docs / tooling / CI
• Refactor (no behavior change)

Release notes

• Not user-facing (no entry needed)
• Added entry to docs/release-notes/unreleased.md

Testing

• Added/updated tests
• pytest (command / notes):
• Other validation (benchmarks, docs build, examples):

Backwards compatibility

• No breaking changes
• Potentially breaking (describe + rationale)

Checklist

• PR base branch is develop
• CI is green
• Docs/docstrings updated where appropriate

[mhostetter]

Sorry, I think I missed this. Thanks for submitting.

Is this a bug fix? Can you summarize the bug and fix? Or is it a performance improvement?

[bwesterb]

Would you call a sort function that takes O(n^2) time a performance issue or a bug? Anyway, it's like that: in even characteristic the present algorithm doesn't work well and comes down to guessing a factor. See #654 for the details.