migrate_gists.py

import requests
import subprocess

GITHUB_API = "https://api.github.com"
GITHUB_PAT = "<personal-access-token>"
OLD_USER = "<username>"
NEW_USER = "<username>"

gists = requests.get(GITHUB_API + "/users/" + OLD_USER + "/gists").json()
for gist in gists:
    gist_id = gist["id"]
    git_pull_url = gist["git_pull_url"]
    subprocess.call("git clone " + git_pull_url, shell=True)
    response = requests.post(GITHUB_API + "/gists", json={
        "files": {
            "temp.txt": {
                "content": "hello world"
            }
        },
        "public": True
    }, auth=(NEW_USER, GITHUB_PAT)).json()
    git_push_url = response["git_push_url"]
    subprocess.call("cd " + gist_id + " && git remote set-url origin " + git_push_url + " && git push -u origin master --force && cd ..", shell=True)