Fix missing '

jhub_remote_user_authenticator/remote_user_auth.py

@@ -57,7 +57,7 @@ class RemoteUserAuthenticator(Authenticator):
         ]
     
     def login_url(self, base_url):
-        return self.domain + '/Shibboleth.sso/Login
+        return self.domain + '/Shibboleth.sso/Login'
 
     def logout_url(self, base_url):
         return self.domain + '/Shibboleth.sso/Logout?return=/'