Give passwords to each user created in support of an ECPG connection
test case. Use SET SESSION AUTHORIZATION, not a fresh connection, to
reduce privileges during a dblink test case.
To test against such a server, both the "make installcheck-world"
environment and the postmaster environment must provide the default
user's password; $PGPASSFILE is the principal way to do so. (The
postmaster environment needs it for dblink and postgres_fdw tests.)
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