Installer is broken on develop

( ! ) Fatal error: Uncaught exception 'ReflectionException' with message 'Class does not exist' in /home/pie/apps/git-phpbb/deps/Symfony/Component/DependencyInjection/ContainerBuilder.php on line 762
( ! ) ReflectionException: Class does not exist in /home/pie/apps/git-phpbb/deps/Symfony/Component/DependencyInjection/ContainerBuilder.php on line 762
Call Stack

1. Time Memory Function Location
   1 0.0014 385384 {main}

   ( ) ../index.php:0
   2 0.1720 4353760 Symfony\Component\DependencyInjection\ContainerBuilder->get( ) ../index.php:105
   3 0.1721 4361272 Symfony\Component\DependencyInjection\ContainerBuilder->createService( ) ../ContainerBuilder.php:353
   4 0.1723 4362088 Symfony\Component\DependencyInjection\ContainerBuilder->resolveServices( ) ../ContainerBuilder.php:749
   5 0.1723 4362888 Symfony\Component\DependencyInjection\ContainerBuilder->resolveServices( ) ../ContainerBuilder.php:828
   6 0.1724 4362968 Symfony\Component\DependencyInjection\ContainerBuilder->get( ) ../ContainerBuilder.php:831
   7 0.1725 4379112 Symfony\Component\DependencyInjection\ContainerBuilder->createService( ) ../ContainerBuilder.php:353
   8 0.1726 4379672 Symfony\Component\DependencyInjection\ContainerBuilder->resolveServices( ) ../ContainerBuilder.php:749
   9 0.1726 4380248 Symfony\Component\DependencyInjection\ContainerBuilder->resolveServices( ) ../ContainerBuilder.php:828
   10 0.1726 4380328 Symfony\Component\DependencyInjection\ContainerBuilder->get( ) ../ContainerBuilder.php:831
   11 0.1728 4405024 Symfony\Component\DependencyInjection\ContainerBuilder->createService( ) ../ContainerBuilder.php:353
   12 0.1729 4405376 ReflectionClass->__construct( ) ../ContainerBuilder.php:762

(18:12:33) igorw: nn-1: I think injecting db into cache broke installation
(18:14:03) igorw: on the install/index.php db.conn does not exist
(18:18:42) igorw: however I think I may have found a relatively clean way to fix it
(18:19:33) igorw: it looks like the only reason we need $cache at all is because of obtain_hooks(), so if we extract that into a separate class, we only need to change those calls to use the new one
(18:19:58) igorw: and it only needs to be changed in 3 place
(18:19:59) igorw: s