[git] Git refusing to merge unrelated histories on rebase

I see the most voted answer doesn't solve this question, which is in the context of rebasing.

The only way to synchronize the two diverged branches is to merge them back together, resulting in an extra merge commit and two sets of commits that contain the same changes (the original ones, and the ones from your rebased branch). Needless to say, this is a very confusing situation.

So, before you run git rebase, always ask yourself, “Is anyone else looking at this branch?” If the answer is yes, take your hands off the keyboard and start thinking about a non-destructive way to make your changes (e.g., the git revert command). Otherwise, you’re safe to re-write history as much as you like.

Reference: https://www.atlassian.com/git/tutorials/merging-vs-rebasing#the-golden-rule-of-rebasing