Username sanitization silently remove diacritic & such
|Reported by:||Jbb||Owned by:||sivel|
As per #13159
Manually adding user (backend User->Add new) allow for any username (for example, Dédé) without any error. But WP silently sanitize the username (Dd in my example), so the admin has no idea something went wrong.
Also, Self registration indicate a “Invalid username” error, without any more explanation. Some textual explanation about what's ok and what not might be helpful.