    def _connect_url_add_prefix(self, proposal):
        """Ensure connect_url includes base_url"""
        if not proposal.value:
            # Don't add the prefix if the setting is being cleared
            return proposal.value
        urlinfo = urlparse(proposal.value)
        if not urlinfo.path.startswith(self.base_url):
            urlinfo = urlinfo._replace(path=self.base_url)
            return urlunparse(urlinfo)
        return proposal.value
Ensure connect_url includes base_url
jupyterhub/objects.py