The last caller of this routine was removed in b4166911, and as a wise
man said one day, dead code tends to silently break.

Per discussion between Fujii Masao, Peter Geoghegan, Vignesh C and me.

Reported-by: Peter Geoghegan
Discussion: https://postgr.es/m/CAH2-Wz=sg5H8-vG4d5UmAofdcRMpeTDt2K-NUWp4GSfhenRGAQ@mail.gmail.com