change-default-branch.py

#!/usr/bin/python3

from github import Github # requires pip3 install pygithub

g = Github(input("Enter token: "))
org = g.get_organization(input("Enter org name: "))
branch = input("Enter branch: ")

for repo in org.get_repos():
    try:
        repo.edit(default_branch=branch)
        print(repo.name, "success")
    except:
        print(repo.name, "failed")
        pass