Trying to post a cross-reference as an answer results in the answer being converted into a comment.
But thou shalt not answer in the comments; comments are for suggesting more information or making improvements or similar. Answers belong in answers.
Duplicating the content of the answer seems like a bad idea.
Voting to close as duplicate is probably wrong as well — my impression is that the new question is not identical enough to make people happy with that action. (also, the old post doesn't have an accepted answer, if that matters)
What to do?