Don't rely on include_path to include files.

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

props ketwaroo, hakre.
fixes #17092.


git-svn-id: https://develop.svn.wordpress.org/trunk@25616 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/network/upgrade.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.' ) );
@@ -33,7 +33,7 @@ get_current_screen()->set_help_sidebar(
 	'<p>' . __('<a href="http://wordpress.org/support/" target="_blank">Support Forums</a>') . '</p>'
 );
 
-require_once('../admin-header.php');
+require_once( ABSPATH . 'wp-admin/admin-header.php' );
 
 if ( ! current_user_can( 'manage_network' ) )
 	wp_die( __( 'You do not have permission to access this page.' ) );
@@ -99,4 +99,4 @@ switch ( $action ) {
 ?>
 </div>
 
-<?php include('../admin-footer.php'); ?>
+<?php include( ABSPATH . 'wp-admin/admin-footer.php' ); ?>