Well, the easiest way is to use

but if you don’t want to update all bundles and waste an hour of your time, you can use:

where <app> is placeholder for you app dir, like “app/frontend” or “app/backend”
in case you don’t have build_bootstrap.php on path above (it works for Symfony 2.7.x) just search for it inside vendor\sensio\distribution-bundle\Sensio\Bundle\DistributionBundle