Users with a whitespace in username cannot add favourites or apply page restriction

Users (local or LDAP) with a whitespace in their usernames receive the follwoing error when trying to add a favourite:

~<first half of the username> contains invalid characters ( , !, #, &, (, ), *, ,, ., :, ;, <, >, ?, @, [, ], ^).,<second half of the username>:favourite contains invalid characters ( , !, #, &, (, ), *, ,, ., :, ;, <, >, ?, @, [, ], ^).Close

For example, for the username "thomas eriksen", the error message is:

~thomas contains invalid characters ( , !, #, &, (, ), *, ,, ., :, ;, <, >, ?, @, [, ], ^).,eriksen:favourite contains invalid characters ( , !, #, &, (, ), *, ,, ., :, ;, <, >, ?, @, [, ], ^).Close

Notice the username is truncated/ignored after the whitespace.