When adding the CI integration, I discovered that t/08-postgresql_conf.t would fail if the tests are run as root. Everything else was fine.
For now I've just skipped the offending parts, but it would be good to fix them up.
The issue is that postgresql refuses to start if it's run as root. The main Test::PostgreSQL has code to detect uid=0 and launch postgresql as another uid, but this particular test doesn't do that, so fails.