- The user renaming function has zero test coverage.
- This patch brings that up to speed to test for various scenarios and
ensure that in a normal workflow the correct things has changed to their
respective new value. Most scenarios are to ensure certain things DO NOT
happen.
(cherry picked from commit 5b9d34ed115c9ef24012b8027959ea0afdcb4e2d)
Refs: https://codeberg.org/forgejo/forgejo/pulls/1156
Co-authored-by: Gusted <postmaster@gusted.xyz>