Per Tom Lane, the old test sometimes times out with CLOBBER_CACHE_ALWAYS.

Nathan Bossart

Discussion: http://postgr.es/m/28614.1512583046@sss.pgh.pa.us

Hopefully, the additional logging will help avoid confusion that
could otherwise result.

Nathan Bossart, reviewed by Michael Paquier, Fabrízio Mello, and me