I've never heard that term applied to that definition.
In fact, I know the real etymology of the word.
You can tell it was just slang for a black person -- In Spanish, black is "negro". In Latin, it's "niger".
I'm not sure when it became a derogatory term.
What's interesting is that even today, the term has a second meaning -- "fellow of my ethnicity", "brother", etc. which can only be used by fellows of that race.
Matthew