FYI: I've been shepherding the external containerizer work that Till (and others!) have been working on and as of tonight we've committed one of the last big pieces.
*However,* *this is still incomplete!* Till will be cleaning up some aspects in the next few days, including properly implementing the new Containerizer::containers callback which was added while he was working on the ExternalContainerizer. We'll report back here once we believe others can start using this in their setups.
