The odd part is that the 'dialect' of the minstrel incorporates much of white immigrant country or regional, dialect, better known to the white performers than the black dialects. Much of it can be found in UK dialects of the past.
Gwine, often excoriated, came from England, esp. Sussex but also Isle of Wight.
The slaves, who had to learn English to communicate, picked it up from overseers and people they came in contact with on the plantations, delivering the products of the plantation to market, dock, etc.- not the plantation owners.
They picked up usages and accents of the less well-educated, often fairly recent immigrants.
These words have something to teach us, but often it is not what seems 'obvious'.

Wackipedia, as noted in Mudcat by other posters than myself, lacks peer review or basis in research. It has the value of trash blowing in the wind.