message: nydus-test: directly return enable_validation for v6
  Rafsv6 does not support fs tree validation.
diff: @@ -213,6 +213,9 @@ class RafsConf:
  return self
  def enable_validation(self):
  + if int(self.anchor.fs_version) == 6:
  + return self
  +
  self._configure_rafs("digest_validate", True)
  return self
  