Currently, Scap only supports deploying the master branch of the service deploy repo. Generally, this works well for normal deployment pipeline for simple features, however, for more complicated and risky deployments this is not enough.
When some code is merged into deployment repo master, deployment of other features/fixes is blocked until the HEAD of the master is deployed into production. For risky, large changes, we sometimes need to hold a change in the beta cluster, or on canary nodes in production for an extended period of time and during that period we're effectively blocked out of deployments. If the need for a quick fix arises we're facing a complex situation when the master of the deploy repo has to be reset to the same state as currently deployed into production. In order to avoid that, we would like to be able to create feature branches in the deploy repo of the service and deploy them via scap, thus we need the ability to deploy via scap from a branch other than the master branch.