Hi Robert,
On pgsql-committers Andres reported one concern about test case failure with installcheck with local settings.
(Sorry, I have not subscribed to that mailing list and thus not able to reply there).
Attached patch which fixes that.
However, I am not sure whether it is expected to have stable regression run with installcheck having local settings.
For example, If I have enabale_hashagg = false locally; I will definitely see failures.
ISTM, that I am missing Andres point here.