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/upgrade.php

@@ -15,7 +15,7 @@
 define( 'WP_INSTALLING', true );
 
 /** Load WordPress Bootstrap */
-require( '../wp-load.php' );
+require( dirname( dirname( __FILE__ ) ) . '/wp-load.php' );
 
 nocache_headers();