David Rowley, who also was the primary author of the patch that
added this function; the attribution in my previous commit,
84940644, was incorrect due to
sloppiness on my part.

Discussion: http://postgr.es/m/CAKJS1f_0iSiLQsf_c06AzOWAc3eS6ePjjVQFpcFv3W-O5aktnQ@mail.gmail.com