I honestly don't much care if it's a "master copy" or from Bitkeeper's "master" and "slave" repository -concept, and really the only person who likely knows for sure where it came from is Linus Torvalds. When you say "answered" you mean "speculated".
Master-slave relationships in computing are used to pretty accurately describe exactly what is going on. In case of version control "master" is just a bad name because it's non-descriptive and random, but it wouldn't be the first thing Git has failed at naming in a clear and useful way. Does not mean it is racist.
The word "master" is not purely related to slavery, even though people want to assume that because it fits their narrative. Using master lists, having a master plan, having a blacklist, being a white hat, or wearing a white shirt are all equally racist words, not at all.
Whatever the origin of the word (of which you've only assumed that you know it - not given any proof), it's not a race issue. It's still a bad word that confuses people needlessly and a better name like "default" or e.g. "main" should have always been the right choice. Unfortunately Torvalds makes bad decisions on a regular basis and nobody dares to question him on those because there's some cult of personality thing going on around him.
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