Ticket #17697: 17697.patch

wp-admin/network.php

@@ -523 +523 @@
         // create network tables
         install_network();
         $hostname = get_clean_basedomain();
-        $subdomain_install = !allow_subdomain_install() ? false : (bool) $_POST['subdomain_install'];
+        $subdomain_install = allow_subdomain_install() ? !empty( $_POST['subdomain_install'] ) : false; 
         if ( ! network_domain_check() ) {
                 $result = populate_network( 1, get_clean_basedomain(), sanitize_email( $_POST['email'] ), stripslashes( $_POST['sitename'] ), $base, $subdomain_install );
                 if ( is_wp_error( $result ) ) {