Mostly the latter, which of course makes it easier. The open source parts are either only open source in that they're publicly available but in reality there's

Mostly the latter, which of course makes it easier. The open source parts are either only open source in that they're publicly available but in reality there's no other users (we know of) or there aren't many users and they just deal with it e.g. in case of a fork of a more popular project where we have a feature branch which gets rebased on upstream regularly.