Re: Thornier
Copyright is not an issue when forking. As long as all the code was covered by the Apache license at the time of the fork, and no later changes obtained from the copyright holder are later incorporated, that grants the use of the copyrighted work, regardless of whether the copyright holder wants to change the license.
Now trademarks are another issue. I agree that a forked product would not be allowed to use anything that is trademarked, like the name of the product or service (assuming it is trademarked), although when generic words in the English dictionary are used, it sometimes becomes more difficult to defend the mark. You could not call it "ElasticSearch", but variants including the words "elastic" and "search" (maybe not in that order) probably could be used.
Biting the hand that feeds IT
