Fixed #35530 -- Deprecated request.user fallback in auth.login.

[jaap3]

Trac ticket number

ticket-35530

Branch description

Removed request.user fallback logic in auth.login. There is no clear reason for it to exist, hasn't been tested until recently (through the async wraper) and is confusing at best.

Checklist

• [x] This PR targets the main branch.
• [x] The commit message is written in past tense, mentions the ticket number, and ends with a period.
• [x] I have checked the "Has patch" ticket flag in the Trac system.
• [x] I have added or updated relevant tests.
• [ ] I have added or updated relevant docs, including release notes if applicable.
• [ ] I have attached screenshots in both light and dark modes for any UI changes.

[jaap3]

Thanks Mariusz, does that mean that this is acceptable? Should I add the deprecation to the release notes?

[jaap3]

Thanks @nessita, I'm a bit busy at the moment, have to find some time to get to this

[nessita]

Thanks @nessita, I'm a bit busy at the moment, have to find some time to get to this

No problem @jaap3, thank all the time you need. When this is ready for re-review, just update flags in the Trac ticket. Thank you!

[jaap3]

@nessita I've addressed your comments. Hope I did it right.

[jaap3]

@sarahboyce thanks for the review, I've addressed your comments. I've chosen to keep the new test module since your comment was inconclusive and I don't think these tests belong in the auth backends test suite.