That's true, but it sounds rather informal. A risk-adverse company would probably want you to assign copyright formally. They need to know what they own and wha

That's true, but it sounds rather informal. A risk-adverse company would probably want you to assign copyright formally. They need to know what they own and what they have a license for. Otherwise, the situation will be confusing when someone comes along years later. "Hmm, this code looks familiar. Wait, why do we have a copy of GPL-licensed code in our system, with the licenses removed?"