packer: only show git commit in version output for prerelease
packer: only show git commit in version output for prerelease

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