Because commit ea69a0de bumped the
HASH_VERSION, we don't need to worry about PostgreSQL 10 seeing
bucket pages from earlier versions.

Amit Kapila

Discussion: http://postgr.es/m/CAA4eK1LAo4DGwh+mi-G3U8Pj1WkBBeFL38xdCnUHJv1z4bZFkQ@mail.gmail.com