Why Git suxx

$ git checkout master
Already on 'master'
Your branch is up-to-date with 'origin/master'.

$ git checkout https://github.com/gratipay/grtp.co/pull/178
 Checkout aborted
 There's no file https:\github.com\gratipay\grtp.co\pull\178 at HEAD

$ git switch https://github.com/gratipay/grtp.co/pull/178
git: 'switch' is not a git command. See 'git --help'.

Solution

Download https://github.com/tj/git-extras/blob/master/bin/git-pr to your git --exec-path.