hack/build: Pin to RHCOS 47.212 and quay.io/openshift-release-dev/ocp-release:4.0.0-6#918

wking wants to merge 2 commits intoopenshift:masteropenshift/installer:masterfrom

wking:version-0.7.0-pinswking/openshift-installer:version-0.7.0-pinsCopy head branch name to clipboard