Merge lp:~ubuntu-on-ec2/vmbuilder/jenkins_kvm-drop-docker-preload into lp:~ubuntu-on-ec2/vmbuilder/jenkins_kvm [a=tobijk] [r=davidkrauser,rcj]
Drop pre-caching of docker.io and docker-compose
MP: https://code.launchpad.net/~ubuntu-on-ec2/vmbuilder/jenkins_kvm-drop-docker-preload/+merge/364491