"Matt, I don't know that a black person would need to identify the girl as black. Why not just "girl"? I understand your point, though. I just don't know that I'd agree with it. In all cases."

Well whether he needed to or not, that's what the (black) musician Leadbelly sang when he recorded it.

It would be interesting to hear Rhiannon Giddens or Dom Flemons perspective on that song and those particular lines - it is a patriarchal/macho/threatening address ('black girl, black girl, don't lie to me, tell me where did you sleep last night?). But unquestionably much more so when coming from the mouth of a white person.