A patch applied to a singular work for the purposes of modifying it, I think the law could easily decide that the patch itself is a derivative work of the origi

A patch applied to a singular work for the purposes of modifying it, I think the law could easily decide that the patch itself is a derivative work of the original. A derivative work does not have to contain anything of the original -- it just has to be made from it in some way. However, something that it's own generic work or not copyrightable (like a block list) would then not be considered a derivative work.