I don't understand why you want to rebase in this scenario. All you're doing is throwing away information (the point where the branch diverged), but you're not

I don't understand why you want to rebase in this scenario. All you're doing is throwing away information (the point where the branch diverged), but you're not recovering anything or making the history any "cleaner". Not only this, but you're introducing a potential for error, because a branch that merges cleanly may not necessarily rebase cleanly (e.g. if the branch made a change that would conflict, but then backed out that change in a subsequent commit).