def lookup_pimlico_versions():
    # Use Github API to find all tagged releases
    tag_api_url = "%s/repos/markgw/pimlico/tags" % GITHUB_API
    try:
        tag_response = urlopen(tag_api_url).read().decode("utf-8")
    except Exception as e:
        print("Could not fetch Pimlico release tags from {}: {}".format(tag_api_url, e))
        sys.exit(1)
    tag_data = json.loads(tag_response)
    return [tag["name"] for tag in reversed(tag_data)]