code: func needsDefaultScale(appID, prevReleaseID string, procs map[string]ct.ProcessType, client controller.Client) bool {
  	if _, ok := procs["web"]; !ok {
  		return false
  	}
  	if prevReleaseID == "" {
  		return true
  	}
  	_, err := client.GetFormation(appID, prevReleaseID)
  	return err == controller.ErrNotFound
  }
docs: // needsDefaultScale indicates whether a release needs a default scale based on
  // whether it has a web process type and either has no previous release or no
  // previous scale.