Index: src/wp-signup.php
===================================================================
--- src/wp-signup.php	(revision 25017)
+++ src/wp-signup.php	(working copy)
@@ -511,10 +511,7 @@
 }
 
 // Main
-$active_signup = get_site_option( 'registration' );
-if ( !$active_signup )
-	$active_signup = 'all';
-
+$active_signup = get_site_option( 'registration', 'none' );
 $active_signup = apply_filters( 'wpmu_active_signup', $active_signup ); // return "all", "none", "blog" or "user"
 
 // Make the signup type translatable.