message: Don't delete console builder image. Otherwise we re-download it every build, wasting resources and slowing build times.
diff: @@ -87,7 +87,13 @@ else
  fi
  echo "Cleaning up old Docker images..."
  -docker rm $(docker ps -a -q) || true # delete stopped containeres
  -docker rmi $(docker images -q) || true # delete images (fails on images currently used)
  -docker volume ls -qf dangling=true | xargs -r docker volume rm || true # delete orphaned volumes
  +# delete stopped containers
  +docker rm $(docker ps -a -q) || true
  +
  +# delete images except for console builder (fails on images currently used)
  +TO_DELETE=$(docker images | grep -F -v quay.io/coreos/tectonic-console-builder | awk '{print $3}' | grep -v IMAGE)
  +docker rmi $TO_DELETE || true
  +
  +# delete orphaned volumes
  +docker volume ls -qf dangling=true | xargs -r docker volume rm || true
  echo "Done!"
  