Reported by Mathias Bavay, Jun 1, 2011

When promoting a user from "extra authorized" to 
"project member", if his user name is left in the extra 
authorized list, he will not get project member rights (at least in 
svn). 

This is not wrong per see, but displaying a warning message that the 
user is already listed in "extra authorized users" would 
be extremely helpful (and avoid spending hours trying to debug svn).