commit 06e9441321598fa49519c507b659985cb1c3c741
Author: Varun Agrawal <Varun@VarunAgw.com>
Date:   Thu Feb 6 05:23:40 2014 +0530

    Fixed bug #25802. Unexpected redirect if you try to visit non-existant wp-admin (Multisite)

diff --git wp-admin/admin.php wp-admin/admin.php
index a617d11..2c5f5da 100644
--- wp-admin/admin.php
+++ wp-admin/admin.php
@@ -29,6 +29,12 @@ if ( isset($_GET['import']) && !defined('WP_LOAD_IMPORTERS') )
 
 require_once(dirname(dirname(__FILE__)) . '/wp-load.php');
 
+
+if ( $path <> $current_blog->path ) {
+    header( 'Location: /',  301);
+    die;
+}
+
 nocache_headers();
 
 if ( get_option('db_upgraded') ) {