But even the use of the word "master" as it relates to the primary copy seems to be related to a master, as in one who guides or rules others. So that seems to still be related to the master/servant relationship. I'm not an etymologist, so someone could point an error here.
The point isn't that every person from Linus on has been engaged in a giant conspiracy to spread hate via git repos (Side note: would there be a secret code you can interpret by arranging hashes in a particular order?). The point is really that our language and culture contain countless reminders of the belief that not all people should be treated with equal value, to the point that we've been using them without regard to or even understanding of their impact.