If I am creating a PR for a branch that already exists, I get this message:
"An existing pull request will be updated #563: [PR title] (created 5 minutes ago)"
The "#563: [PR title]" part is a link to the PR that would be updated, but when I click the link, I just end up where I am. You should either remove the link (keep the text) or have it actually go somewhere else.
I'm guessing it would be fairly easy to fix. The data is already there in the HTML.