merge-repos.py

#!/usr/bin/env python
import os
import subprocess
from git import Repo

working_dir = os.getcwd()

repo = Repo(working_dir)

origin_branches = list()
old_branches = list()
branches = list()

for ref in repo.git.branch('-r').split('\n'):
    branch = ref.strip()

    if branch.startswith('old/'):
        old_branches.append(branch.replace('old/', ''))
    elif branch.startswith('origin/'):
        origin_branches.append(branch.replace('origin/', ''))

for old_branch in old_branches:
    if old_branch not in origin_branches:
        subprocess.call(['git', 'checkout', f'old/{old_branch}'])
        subprocess.call(['git', 'switch', '-c', old_branch])
        subprocess.call(['git', 'push'])
    else:
        if old_branch != 'master':
            subprocess.call(['git', 'push', '-d', 'old', old_branch])