be more cautious

Author: ksqsf

src/rime/gear/reverse_lookup_filter.cc

@@ -79,7 +79,7 @@ void ReverseLookupFilter::Process(const an<Candidate>& cand) {
   if (rev_dict_->ReverseLookup(phrase->text(), &codes)) {
     comment_formatter_.Apply(&codes);
     if (!codes.empty()) {
-      if (!overwrite_comment_ && !append_comment_) {
+      if (!overwrite_comment_ && !append_comment_ && cand->comment().empty()) {
         phrase->set_comment(codes);
       } else if (overwrite_comment_) {
         phrase->set_comment(codes);