When you have a domain domainb.com, sub-server of another domain domaina.com and move domainb to create an independent virtualserver the result is this.
If you had postgresql activated in domaina.com, when you try to activate it in domainb with domainb already moved you get this error:
Failed to modify server : A PostgreSQL login named domaina.com is already owned by virtual server domaina.com. You note tha we are activating domainb postgresql, not domaina.
If you deactivate postgresql in domaina previously to activate it in domainb you can see that when you to webmin, postgresql, users you have a new user called domaina.com, but you ote tha we were trying to activate domainb.com.
I have see it after a migration from one to other server, whe recover backup of domainb.
The great big fail is that i cannot assign the users of domainb to admin the postgresql databases of domainb.