Our friend Tilmen provides some photographic evidence...
4: here is another pic showing how Ubisoft replaced that black slave in #AC4BlackFlag ...only in that scene btw pic.twitter.com/6wqyNkLbMA
— NiNTENDOMiNATiON (@TiLMEN) November 1, 2013
Obviously Tilmen has played at least the Wii U version, but this seems to be a change in all US versions. Doesn't look like a lighting change here. Looks more like a race swap from black to white. Certainly an interesting find, if true. I wonder what the reasoning behind it is.