If my pull request branch name is "feature/follow", everything blows up!
From what I am understanding, you are not doing any name blacklisting on pull request URLs. For this reason, if my branch is called "feature/follow", my pull request name will be "../pull-request/21/follow", which conflicts with the existing route for following/unfollowing a pull request.
This ends up in an infinite redirect loop.
Please let me know if I can contribute somehow, if you want you can assign this to me. I would be very happy to contribute.