Interesting. We've never had tests for that even for "service". Perhaps it would be the time to add some tests for the existing case and the one you are adding? Your test suite should make that easy to add.
Currently, a lot of our utility scripts (anything that uses connectDatabase) don't support service=name params or PGSERVICE=name env vars, which is really too bad. I previously thought that this was because of a lack of interest, but perhaps people do want it?