hyrax's latest report suggests that this patch has issues under
CLOBBER_CACHE_ALWAYS:
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=hyrax&dt=2020-08-13%2005%3A09%3A58
Hard to tell whether there's an actual bug there or just test instability,
but either way it needs to be resolved.
regards, tom lane