Не работает cron.php на Drupal

Warning: include_once(./includes/bootstrap.inc): failed to open stream: No such file or directory in /var/www/user/data/www/site.com/cron.php on line 8

Warning: include_once(): Failed opening './includes/bootstrap.inc' for inclusion (include_path='.:/usr/share/php:/usr/share/pear') in /var/www/user/data/www/site.com/cron.php on line 8

Fatal error: Call to undefined function drupal_bootstrap() in /var/www/user/data/www/site.com/cron.php on line 9

А исправляется это заменой вызова

php -f /var/www/user/data/www/site.com/cron.php

в кроне на

wget -q http://site.com/cron.php