patch for unicode(multibyte) username

below line filters unicode username that is accepted at 5.x..
but, I don`t know if it can cause futher problem...

diff -u user_import/user_import.module user_import./user_import.module
--- user_import/user_import.module 2007-03-13 02:40:06.000000000 +0900
+++ user_import./user_import.module 2007-05-02 15:21:56.000000000 +0900
@@ -1120,7 +1120,8 @@
if ($sanitised == 0) {

// username cannot contain an illegal character
- $username = preg_replace('/[^a-zA-Z0-9@._\- ]/', ' ', $username);
+ // this filters a unicode(multibyte) user name.
+ //$username = preg_replace('/[^a-zA-Z0-9@._\- ]/', ' ', $username);
// username cannot contain multiple spaces in a row
$username = preg_replace('/[ ]+/', ' ', $username);