Checking out GitHub pull requests locally

When working with GitHub you often need to checkout a pull request (PR) locally so you can load it in your favorite tools and run/test it.

GitHub help suggests you can use a command similar to:

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

(here ID is the number of the pull request)

While this will give you the original code of the PR, it might be different from what you will get if you actually merge the PR. The reason is that you might have parallel changes in your target (master) branch not yet merged in the PR. While you can do the merge also locally, it turns out this is not necessary as GitHub had alsready done it for you. All you need is to use this command instead:

git fetch origin pull/ID/merge && git checkout FETCH_HEAD

(notice the difference in the refspec 'head' vs. 'merge')

This will give you a merged version of the PR which contains all parallel commits in the target branch even those merged after the PR was created.