def cmd_rollback_to(context):
  """
  Roll back by finding a specific version in the history of the service and
  putting it as the new current version.
  Args:
    context: a populated EFVersionContext object
  """
  version = get_version_by_value(context, context.rollback_to)
  context.value = version.value
  context.commit_hash = version.commit_hash
  context.build_number = version.build_number
  context.location = version.location
  context.stable = True
  cmd_set(context)