<a href="https:&#x2F;&#x2F;reviewable.io" rel="nofollow">https:&#x2F;&#x2F;reviewable.io</a> deals with changes in this way and has no problems with rebasing, even distinguishing between deltas in the branch vs the base when diffing. Only works on top of GitHub, though, sorry.  (Disclosure: I&#x27;m the founder.)