Thanks for the patch -- I have pushed it now, with some wording changes and renaming the role to regress_* to avoid buildfarm's ire.
Michaël in addition proposes an isolation test. I'm not sure; is it worth the additional test run time? It doesn't seem a critical issue. But if anybody feels like contributing one, step right ahead. -- Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
