This reverts commit a052f6cb, following complains from Robert Haas and
Tom Lane.  Backpatch down to 9.4, like the previous commit.

Discussion: https://postgr.es/m/CA+TgmobL4npEX5=E5h=5Jm_9mZun3MT39Kq2suJFVeamc9skSQ@mail.gmail.com
Backpatch-through: 9.4