Created by: hshen14

In is_test pass, the code will check the whether op has attribute or op defines is_test first and then whether op exists in the specified op_list.

 for (const Node* n : graph->Nodes()) {
    if (n->IsOp()) {
      auto* op = n->Op();
      if (op->HasAttr("is_test") || op->HasProtoAttr("is_test")) {
        op->SetAttr("is_test", true);
      } else if (std::find(begin(op_list), end(op_list), op->Type()) !=
                 end(op_list)) {
        op->MutableAttrMap()->insert(
            std::pair<std::string, Attribute>("is_test", true));
      }
}

The right logic should check op first and then the op attribute. Please consider to fix it. @kbinias