Nextcloud-vue: User mention in comment field does not work for users with @ in name

[roadrunnerjb]

First I thougt its solved with NC21. Selction works but we have users with special chars as "@" in their usernames. When I select one of those users the "@" inside the username is removed and so the user mention does not work

_Originally posted by @roadrunnerjb in https://github.com/nextcloud/server/issues/19523#issuecomment-810150432_

[kesselb]

cc @skjnldsv @nickvergessen

[skjnldsv]

Oooh!
I was not even aware we allowed @ in uids :cry:
cc @rullzer @blizzz, isn't there a discussion about special chars i uids?

[nickvergessen]

@ is allowed as a lot of people use email addresses alike syntax for the user id:
https://github.com/nextcloud/server/blob/master/lib/private/User/Manager.php#L413-L418

Registration app also has an option that forces the validated email as user id, so that has to be fixed here.

[nickvergessen]

https://github.com/nextcloud/server/issues/21313 for discussion

[skjnldsv]

I guess this should move to the vue components?
As this is where the autocomplete takes place :)