post-processor: Recognize the virtualbox builder
post-processor: Recognize the virtualbox builder

suma/packer,zyegfryed/packer,msabramo/packer,Kaixiang/packer,zyegfryed/packer,Kaixiang/packer,patricklucas/packer,suma/packer,smerrill/packer,suma/packer,TranscendComputing/packer,smerrill/packer,suma/packer,Kaixiang/packer,zyegfryed/packer,msabramo/packer,patricklucas/packer,zyegfryed/packer,smerrill/packer,patricklucas/packer,msabramo/packer,smerrill/packer,Kaixiang/packer,TranscendComputing/packer,patricklucas/packer,msabramo/packer,TranscendComputing/packer,TranscendComputing/packer