How can I fetch an unmerged pull request for a branch I don't own?

Question

To fetch a pull into your repository:

git fetch [email protected]:jboss/jboss-common-beans.git refs/pull/4/head

Then do whatever you want with FETCH_HEAD:

git checkout -b new-branch FETCH_HEAD

git pull origin pull/28/head

Or

git fetch origin pull/28/head:28
git checkout 28

Can I pull a not-yet-merged pull request?

You can do this:

1) Add the upstream remote:

git remote add upstream [email protected]:Particular/NServiceBus.git

2) After that, you can checkout any pull request to a new branch per its ID:

git fetch upstream pull/PULL_REQUEST_ID/head:NEW_BRANCH_NAME

Then you'll have a branch named NEW_BRANCH_NAME containing the PR code.

Adding an alias:

If you do this as often as me, you may want to setup some aliases for it. I have this in my .gitconfig:

[alias]
    fetch-pr = "!f(){\
        [ -z \"$1\" ] && { echo Usage: git fetch-pr PULL_REQUEST_ID [REMOTE_NAME] [NEW_BRANCH_NAME]; exit 1; }; \
        remote=${2:-origin}; \
        branch=${3:-pr-$1}; \
        git fetch $remote \"pull/$1/head:$branch\"; \
        }; f "
    pr = "!f(){\
        branch=${3:-pr-$1}; \
        git fetch-pr \"$@\"; \
        git switch $branch; \
        }; f "

With the above, I can do:

git fetch-pr 123              # fetch PR #123 into branch pr-123
git fetch-pr 123 some-branch  # fetch PR #123 into some-branch
git pr 123                    # fetch and switch to the branch

For difficult situations (especially if you have not a checked out git-repo), I think the simplest way is to apply a patch. For this just open the pull-request on github and add a ".patch" to the URL, download it and apply the patch.

Example:

cd cordova-plugin-media
wget https://github.com/apache/cordova-plugin-media/pull/120.patch
patch -p1 < 120.patch

See this help article from GitHub: https://help.github.com/articles/checking-out-pull-requests-locally

github/hub

https://github.com/github/hub is a GitHub CLI helper that deals with this and other use cases beautifully using extra information from the GitHub API. E.g.:

git clone https://github.com/github/hub
# Just copy paste the URL.
hub checkout https://github.com/github/hub/pull/970

Result:

• we are now on a branch called <USERID>-<BRANCH_NAME> that contains the PR.

  Note the good branch name which was automatically set for us.

• that branch is set to track the original branch on the fork, i.e. .git/config contains:

  [branch "<USERID>-<BRANCH_NAME>"]
      remote = retronym
      merge = refs/heads/ticket/969
      rebase = true
  

  So if further commits get pushed, we can git fetch them directly.

Installing hub on Linux is currently a pain if you're not familiar with Go, but worth it. On Ubuntu 14.04, the Go on the repositories is too old, so GVM is the best option:

bash < <(curl -LSs 'https://raw.githubusercontent.com/moovweb/gvm/master/binscripts/gvm-installer')
. "$HOME/.gvm/scripts/gvm"
gvm install 'go1.4'
gvm use 'go1.4' --default
go get github.com/github/hub

I have also asked GitHub to give us a copy paste cheatsheet on the web UI at: https://github.com/isaacs/github/issues/449