Honestly, I don't know. I'd suppose it depends more on the sort of thing we're talking about than anything. If it's something like "Obtvse", or a fully formed system and you're copying it outwardly, then probably yes.
If it's a ilbrary that fetches RSS feeds as part of a larger system, I'm guessing no.
Of course, it also depends significantly on the author. If it's a public git repository, one assumes that it's something people wish to be forked.
Though I suppose an interesting experiment would be to publicly post closed source code with a closed source license attached as honeypots and sue everyone that forks / modifies your code base.
