Checkout github pull requests locally

pr.md

Locate the section for your github remote in the .git/config file. It looks like this:

[remote "origin"]
	fetch = +refs/heads/*:refs/remotes/origin/*
	url = [email protected]:joyent/node.git

Now add the line fetch = +refs/pull/*/head:refs/remotes/origin/pr/* to this section. Obviously, change the github url to match your project's URL. It ends up looking like this:

[remote "origin"]
	fetch = +refs/heads/*:refs/remotes/origin/*
	url = [email protected]:joyent/node.git
	fetch = +refs/pull/*/head:refs/remotes/origin/pr/*

Now fetch all the pull requests:

$ git fetch origin
From github.com:joyent/node
 * [new ref]         refs/pull/1000/head -> origin/pr/1000
 * [new ref]         refs/pull/1002/head -> origin/pr/1002
 * [new ref]         refs/pull/1004/head -> origin/pr/1004
 * [new ref]         refs/pull/1009/head -> origin/pr/1009
...

To check out a particular pull request:

$ git checkout pr/999
Branch pr/999 set up to track remote branch pr/999 from origin.
Switched to a new branch 'pr/999'

A decade later this gist is still super useful. I review homework PRs and this workflow makes that a breeze. Thank you @piscisaureus!!

Very cool.

I had to make a small correction for multiple remotes: git checkout upstream/pr/999, which would be nice to add for completeness.
This is much more compact than the github help page.

There is an implementation "oddity" within Git about how this works. The new line added to the [remote "origin"] section does not have to be appended as the last line of that section. It could be inserted as the first line of that section.

Miraculously this makes a difference!

If you get the order correct -- then git pull just works after git checkout pr/1234 😃
This S.O. answer has the details.

No matter what though, as @dougludlow points out, git pull origin refs/pull/1234/head should work even if your branch.pr/1234.merge config value is not correct.

Is this a reasonable python script to clone a repo and add the PR's ?

import subprocess
import os
from git import Repo

def clone_and_configure(github_url, local_path):
    # Perform the initial Git clone
    if os.path.exists(local_path):
        print(f"Local repository already exists in {local_path}. Skipping clone.")
    else:
        # Perform the initial Git clone
        subprocess.run(['git', 'clone', github_url, local_path])
        print(f"Repository cloned to {local_path}.")

    git_path = f'{local_path}/.git/'

    repo = Repo(git_path)
    # Read the existing Git configuration

    repoconfig = repo.config_reader()  # Get a config reader for read-only access.
    
    if any('origin' in key for key in repoconfig.sections()):
        print("found a section with origin")
        for section_name in repoconfig.sections():
            if 'origin' in section_name:
                fetch_line = '+refs/pull/*/head:refs/remotes/origin/pr/*'
                # Which to use ?
                #fetch_line = '+refs/pull/*/head:refs/gh-pull/remotes/origin/*'
                repo.git.config('--add', f'remote.origin.fetch', fetch_line)
                # Update the URL if needed
                repo.remote('origin').set_url(github_url)
    
    #subprocess.run(['git', 'fetch','origin', local_path])
    subprocess.run(['git', 'fetch', 'origin'], cwd=local_path)


def main():
    # Specify your GitHub project URL
    github_url = 'https://github.com/hardikvasa/google-images-download'  # Replace with your project URL
    # Specify the local path where you want to clone the repository
    local_path = 'C:/Users/Simon/Desktop/google-image-downloader'  # Replace with your desired local path

    # Perform the initial Git clone and configure
    clone_and_configure(github_url, local_path)

if __name__ == "__main__":
    main()