Stable release used for bootstrapping nodes conflicts with quickstart repo setup #22
Description
I noticed that repo-setup role failed because of newer packages were installed via user data bootstrap script.
The latter had effectively invoked env STABLE_RELEASE=master tripleo-ci/scripts/tripleo.sh --repo-setup.
The former configured dlrn repos from quicktart's config/release/master-tripleo-ci.yml, which somehow ended up with older packages attempted to be installed and failed.
Not sure how to trace down the root cause of those two produced different configs for 'master' repos, but for traas we prolly should make the bootstrap repo config optional.