Don't rely on include_path to include files.

Always use dirname() or, once available, ABSPATH.

props ketwaroo, hakre.
fixes #17092.

Built from https://develop.svn.wordpress.org/trunk@25616


git-svn-id: http://core.svn.wordpress.org/trunk@25533 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/network/site-themes.php

@@ -8,7 +8,7 @@
  */
 
 /** Load WordPress Administration Bootstrap */
-require_once( './admin.php' );
+require_once( dirname( __FILE__ ) . '/admin.php' );
 
 if ( ! is_multisite() )
 	wp_die( __( 'Multisite support is not enabled.' ) );
@@ -132,7 +132,7 @@ $title = sprintf( __('Edit Site: %s'), $site_url_no_http );
 $parent_file = 'sites.php';
 $submenu_file = 'sites.php';
 
-require('../admin-header.php'); ?>
+require( ABSPATH . 'wp-admin/admin-header.php' ); ?>
 
 <div class="wrap">
 <?php screen_icon('ms-admin'); ?>