Use a `-` as a separator to fix issues with already running detection#990

vb-linetco wants to merge 5 commits intopuppetlabs:mainpuppetlabs/puppetlabs-docker:mainfrom

vb-linetco:955-fix-build-image-name-detectionvb-linetco/puppetlabs-docker:955-fix-build-image-name-detectionCopy head branch name to clipboard