Checking out pull requests locally

Every pull request has two refs in the repository it was opened against, whichever repository its branch lives in:

Both are read-only. A push to either is refused.

Check out a pull requestCopy Anchor Link

git fetch origin pull/42/head:pr-42
git switch pr-42

To update it after the author pushes again:

git fetch origin +pull/42/head:pr-42

Test the merge resultCopy Anchor Link

refs/pull/<number>/merge is rebuilt when either the pull request's branch or its base branch moves, so it tests the code that would actually land:

git fetch origin pull/42/merge
git switch --detach FETCH_HEAD

It does not exist while the pull request conflicts with its base. A CI job that needs it should fall back to merging locally:

git fetch origin +refs/heads/main:refs/remotes/origin/main +refs/pull/42/head:refs/remotes/origin/pr/42
git switch --detach refs/remotes/origin/pr/42
git merge --no-edit refs/remotes/origin/main

Both refs update a few seconds after a push, not at the same instant.

An instance can limit how much a pull request may copy into the repository. When an update is over the limit, the refs stay at the last update that fit and the pull request page says why.

Fetch every pull requestCopy Anchor Link

git config --add remote.origin.fetch '+refs/pull/*/head:refs/remotes/origin/pr/*'
git fetch origin

What stays in the repositoryCopy Anchor Link

Commits pushed to a pull request are copied into the repository it was opened against, and stay there after the branch is force-pushed, the pull request is closed, or the fork is deleted. Ghost cannot remove them. If a secret was pushed to a pull request, rotate it.

A merged pull request's head counts toward the base repository's storage. An unmerged one counts toward nobody's.