def METHOD_NAME(topic):
    if not topic.github_issue:
        return None
    else:
        if topic.github_repository_name:
            repository_name = topic.github_repository_name
        else:
            repository_name = settings.ZDS_APP["github_projects"]["default_repository"]
        bugtracker = get_repository_url(repository_name, "bugtracker")
        return f"{bugtracker}/{topic.github_issue}"