Rebase-friendly alternative to the GitHub "Update Branch" button on the pull request page.
Rebases a remote origin branch onto the latest default branch. Right now, hard coded for "develop" even though most people use "master". Feel free to edit.
I personally use this when I have many remote branches to merge and want all of them to be up-to-date with the latest default branch after each rebase. Of course, if you don't prefer rebase as an updating strategy you can just use the "Update branch" button in the GitHub UI. This is a rebase-friendly alternative.