alt Hacker NewsWrong. This territory was heavily covered in music before this code concept - it has to be “transformative” in the eyes of the law. Even going in and cleaning up code or adding 10-25% new code won’t pass this threshold. Don't bother arguing with me on this, just accept reality and deal with it.
My copy of "Sense and Sensibility and Sea Monsters" is explicitly listed as being copyrighted by Ben H. Winters in 2009 despite the majority of the words being Austen's, though. Perhaps music has different rules compared to text. I suspect Winters and his publisher have investigated the legality of this more than either of us have.