forbiddance of ini_set('include_path', ...) function causes fatal error at revision feature

[codestyling]

The newly introduced revision feature uses PHP ini_set() function but must not. Several provider doesn't permit setting php.ini values especially the include_path, which should be temporary switched during load of Text/Diff files. The fatal error resulting looks like this out of real customer occurance:

Warning: ini_set() has been disabled for security reasons in /srv/www/httpd/phost/l/de/pytalhost/laz/web/wordpress/wp-includes/pluggable.php on line 1517
Warning: require_once(Text/Diff/Renderer.php) [function.require-once]: failed to open stream: No such file or directory in /srv/www/httpd/phost/l/de/pytalhost/laz/web/wordpress/wp-includes/Text/Diff/Renderer/inline.php on line 17
Fatal error: require_once() [function.require]: Failed opening required ‘Text/Diff/Renderer.php’ (include_path=’.:/srv/www/httpd/phost/l/de/pytalhost/laz/web’) in /srv/www/httpd/phost/l/de/pytalhost/laz/web/wordpress/wp-includes/Text/Diff/Renderer/inline.php on line 17

This error affects all editor pages won't longer behave as expected. Moreover some provider doesn't show any errors and silently abort the engine. This results in white pages served!
I have attached a patch suggestion (containing 4 file from WP 2.6.0) which doesn't use ini_set() anymore but all require calls now using _ _FILE_ _ evaluation of their appropriated complete file path. Has been successful tested at this affected system. Can also be simulated, if you comment the ini_set() inside pluggable.php function wp_text_diff().

[codestyling]

sorry, please refere to ​http://trac.wordpress.org/ticket/7391, my browser sends 2 times one without and one with patch.