yeah, this is where my complaint is - github shows a "compare" button when I force push, but it's not linked to the PR review. The "file changed" status is often not granular enough - if I change one line, force push, the entire file gets marked as unreviewed. the github "changes since your last review" is commit-based, not sha-based.

what I want is something like graphite/gerritt/google's critique where after each force push, the review page shows only the true delta between the two shas (similar to the "compare" button in github, bu as a reviewable unit).

poked around on github, doesn't look like the stacked PR feature has affected this "changes since your last review" selector yet :(