Ticket #33804: 33804_3.diff

wp-admin/network/site-new.php

@@ -89 +89 @@
         $password = 'N/A';
         $user_id = email_exists($email);
         if ( !$user_id ) { // Create a new user with a random password
+                $user_id = username_exists($domain);
+                if ( $user_id )
+                        wp_die( __( 'Username already existed.' ) );
                 $password = wp_generate_password( 12, false );
                 $user_id = wpmu_create_user( $domain, $password, $email );
                 if ( false === $user_id )