git-ghpull.sh

#! /usr/bin/env python3
import re
import sys 
import json
import urllib.request
import argparse
import subprocess

# get config
try:
    repo_url = subprocess.check_output(['git', 'remote', 'get-url', 'upstream']).strip().decode('utf-8')
    if not repo_url.startswith('https://'):
        print("`upstream` remote must be an https URL")
        sys.exit(1)
    repo_url = repo_url.split('/')
    owner = repo_url[3]
    repo = re.sub(r'\.git$', '', repo_url[4])
except subprocess.CalledProcessError:
    print("`upstream` remote must exist")
    sys.exit(1)

def main():
    parser = argparse.ArgumentParser(description='Process some integers.')
    parser.add_argument('pullreq', metavar='PR', type=int,
                        help='pull request to pull')
    parser.add_argument('-f', '--force', dest='force', action='store_true',
                        default=False,
                        help='overwrite an existing branch with this name')
    parser.add_argument('-p', '--pr-branch', dest='prbranch', action='store_true',
                        default=False,
                        help='use branch name `pr<PULLREQ>`')

    args = parser.parse_args()

    url = 'https://api.github.com/repos/%s/%s/pulls/%s' % (owner, repo, args.pullreq)
    res = urllib.request.urlopen(url)
    data = json.load(res)

    remote = data['head']['repo']['owner']['login']
    remote_url = data['head']['repo']['clone_url']
    source_ref = data['head']['ref']

    # add the remote if necessary
    try:
        subprocess.check_call(['git', 'remote', 'add', remote, remote_url], stderr=subprocess.DEVNULL)
    except subprocess.CalledProcessError:
        pass

    # fetch its refs
    subprocess.check_call(['git', 'fetch', remote])

    # set up a new branch tracking it
    branch = 'pr{}'.format(args.pullreq) if args.prbranch else source_ref
    try:
        subprocess.check_call(['git', 'checkout', '-B' if args.force else '-b', branch, '--track', '{}/{}'.format(remote, source_ref)])
    except subprocess.CalledProcessError:
        sys.exit(1)

main()