Sources hash can't be configured per environment

For local development i'd like to pass a different "sources.platform.apt.basic" value. I know i can put them into the node definitions, but i don't like to put it into all of them.

So i'm looking for a way to override this on a environment base. i tried in provider.local.json but those are not picked up, and common.local.json is not supported it seems.

(from redmine: created on 2015-12-10, closed on 2016-05-26)