title: How to update local checkedout PR code with the latest commits into PR?
body: <p>I have checked out a PR into my local. Now the PR got updated, how do I update the local branch with the latest commit.
  When I try to do
  <code>git fetch upstream</code>
  <code>git pull origin</code>
  all of them are saying the branch is not present. And that is because it is a PR and not a branch. How do I update my local repo?</p>