Comment by bloppe

If a project switches from an open-source to a closed-source license, then from the outside, it just looks like the project was abandoned. The final commit that was published under the open-source license will always be open source. It's the future commits that are now closed source.

So no, I don't have any specific examples of that happening.

In the case of both Redis and Terraform, the forks were announced after the license change, not before. Indeed, the forks were motivated by the license change. The community didn't get a warning "hey, we're about to change the license, fork it while you still can!". It just changed.

That's what I mean when I say the license change does not apply retroactively. The commit of Terraform that existed before the license change is still open-source. I could create a fork branching off that commit today if I wanted to.