Good clarification. But, do we know that is what everyone does? It's obviously a cultural, rather than a technical limitation. I suspect there are significan

Good clarification. But, do we know that is what everyone does? It's obviously a cultural, rather than a technical limitation. I suspect there are significant bodies of code kept inside corporate forks of upstream (and regularly rebased to them) with only selected parts dribbled out to the public upstream repos by trusted representatives of said copies. But, I have nothing to prove that and the only public traces I would see would be commits to upstream from corporation X.