GitHub seems to have finally started automatically redirecting URLs to old branches:

Demo:

• 404 branch, file: https://github.com/sindresorhus/refined-github/blob/404/package.json
• 404 branch, folder: https://github.com/sindresorhus/refined-github/blob/404/source

So I'm removing this behavior from blob and tree

However, they don't apply this behavior to edit URLs, so I'm leaving the logic just for that:

• 404 branch, edit file: https://github.com/sindresorhus/refined-github/edit/404/package.json

Bugfixes:

• /user/repo/edit/ URLs should not be queried in the loop:
  https://github.com/sindresorhus/refined-github/edit/master/wrong-file
  

Original feature tests in #1558