There have been quite a few instances where that kind of behaviour has occurred - although mostly in chat and such. There's instances it on Reddit's /r/cringe and the like. It probably doesn't happen much on Github since that's more business-like than a more colloquial environment like chat or dating sites or comment threads, but still.
Also apparently not; if you see above, racism is explained not as 'judging by race', but something involving privilege and whatnot. Which is... very hard to judge.
Hahaha. I mean, this is the world we live in now?
I've always been puzzled by the concept of "reverse racism". As far as I can remember I've only heard this term in America (I've lived in 4 different countries before). I've always found that it was a perfect illustration of doublethink. I mean, people realize that "reverse racism" is actually racism right?