symfony/symfony — pull request #5317 by lchenay (2012-08-22 12:57:45+00:00)
Title: Update src/Symfony/Component/DependencyInjection/Container.php

This throw an exception and should not with isset:

'something' exist as service

$this->container->set('something', null);

if (null !== $this->container->get('something')) {
throw new \Exception('Should be null');
}