How can I check out a GitHub pull request with git?

I prefer to fetch and checkout without creating a local branch and to be in HEAD detached state. It allows me quickly to check the pull request without polluting my local machine with unnecessary local branches.

git fetch upstream pull/ID/head && git checkout FETCH_HEAD

where ID is a pull request ID and upstream where is original pull request has been created (it could be origin, for example).

I hope it helps.

This will fetch without you having to name a branch:

git pull origin pull/939/head

How do I get a specific pull request on my machine?

To fetch a remote PR into your local repo,

git fetch origin pull/$ID/head:$BRANCHNAME

where $ID is the pull request id and $BRANCHNAME is the name of the new branch that you want to create. Once you have created the branch, then simply

git checkout $BRANCHNAME

For instance, let's imagine you want to checkout pull request #2 from the origin main branch:

git fetch origin pull/2/head:MASTER

See the official GitHub documentation for more.