Just a note for others:
antires is talking about 'License', and tomp is talking about 'Copyright'.
Antirez is taking a very narrow copying must include a figurative Ctrl-c Ctrl-v. Where as tomp is taking the wider and I think more legally supported(at least as far as art goes) stance that a work can be 100% your own effort but still be a derivative work if it was inspired by an existing work.(i.e. taking a photo of a sculpture is a derivative work )