Currently, pull requests refer to a git repo and a branch and appear to "live-update" when the originating branch changes.

Generally, I find this to be an awesome feature! :D

However, it does seem to surprise some folks, who don't seem to realize that changing that branch is going to affect the PR they submitted. Particularly when they opt to use their master branch.

So I have a few suggestions that may or may not make sense, but I think they might reduce some confusion.

1. add an checkbox option for pull requests to auto-update or not (default to True/checked)
2. ...except for PRs from master branch, default to False there
3. for PRs that do not auto-update, still check, but instead show an alert on the PR giving the option to trigger the update. I think either the requester or project owners should be able to do this.
4. possibly add a flag for projects that allows them to disable auto PR updates