Problem for nicename

Hi
thank you for your great plugin.
I found one problem about nicename.
basically wordpress is specified 50 lenght for nicename aray in database.
when using Arabic character for user name, wordpress changes it to percentage encoding to saving in nicename.
as you know in percentage encoding each character converted to 6 character for example the character ? in Arabic is %d8%ac in percent encoding. so wordpress uses %d8%ac against ? as nicename. therefore for special character usernames longer than 8 character has more than 50 character in percentage format so without any error the registeration page closed but the user not registered.