Ticket #25407: 25407.patch

wp-login.php

@@ -444 +444 @@
 break;
 
 case 'register' :
-        if ( is_multisite() ) {
+        if ( is_multisite() && apply_filters( 'wpmu_redirect_register', true ) ) {
                 // Multisite uses wp-signup.php
                 wp_redirect( apply_filters( 'wp_signup_location', network_site_url('wp-signup.php') ) );
                 exit;