Fixed HTTP Digest auth not being passed user checker

Commit 05be5da1710ab681a04334d58126f8c3d431e3cb added the ability to
configure a user checker on a per firewall basis. However, that commit seems to
have missed updating the HttpDigestFactory.

src/Symfony/Bundle/SecurityBundle/DependencyInjection/Security/Factory/HttpDigestFactory.php

@@ -29,6 +29,7 @@ class HttpDigestFactory implements SecurityFactoryInterface
         $container
             ->setDefinition($provider, new DefinitionDecorator('security.authentication.provider.dao'))
             ->replaceArgument(0, new Reference($userProvider))
+            ->replaceArgument(1, new Reference('security.user_checker.'.$id))
             ->replaceArgument(2, $id)
         ;