Describe the feature or problem you’d like to solve

One PR is closed, but I still want to modify logic based on its changes, just check it out in CLI with the error below:

gh pr checkout 4021

fatal: couldn't find remote ref refs/heads/encode-plus-code
failed to run git: exit status 128

So I had to clone the forked repo and check out that branch. What if the original branch was deleted? How would I check it out then?

Proposed solution

It would be easier for users like me in this case if we supported checking out closed or deleted PR branches.