builder/common: set the proper finalPath if downloading
builder/common: set the proper finalPath if downloading

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