tests:

- concourse check returns ref (if there is a deployment)
- concourse in returns empty dir (if there is no deployment)
- conourse out returns latest ref

shadowing:
- cepler.yml is always head
- .cepler is always head

propagated files don't shadow head files!


*.yml in testflight
change cepler.yml
prepare staging
ensure cepler.yml is clean
- cepler.yml is always head
