This isn’t any serious bug as the username still does not change, however it is a little inconvenient for moderators when viewing action logs for a specific user and they see a username change but it hasn’t actually been changed.
- Go to
/u/[username]/preferences/username. - Attempt to change the username to something that is already taken.
- Press the ‘change’ box when it allows you to.
- This was a bit hard for me, I will assume this will have different outputs and timings in different environments.
Despite the username not changing, it still logs in admin/logs/staff_action_logs as the username being successfully changed:
Just thought I would report it 
Thanks.
