GitHub just announced stacked pull requests in public preview. Instead of reading the changelog and moving on, I decided to actually try it on this same portfolio repo. The problem it solves I've done the manual version of this before: branch off a big feature, realize it's too large to review in one shot, and split it into a chain of branches that each target the previous one. It works, but every rebase is manual, and if the bottom branch changes, you're rebasing the whole cha...