Error 403 on /devtools/

Hi,

When I launch this command ponyd serve --listen-interface=127.0.0.1 -v I get the following result when I try to access the web interface http://127.0.0.1:9000/devtools/

[W 160613 18:31:29 web:1521] 403 GET /devtools/ (127.0.0.1):  is not a file
[W 160613 18:31:29 web:1946] 403 GET /devtools/ (127.0.0.1) 2.29ms

I'm running it on Python 2.7.11. Do you have any idea why I get these

I set the rights for the directory src/devtools/ to be sure I can access the directory, but I still got this problem, I really don't understand where it could come from !

It seems like an error from Tornade see http://stackoverflow.com/questions/24851207/tornado-403-get-warning-when-opening-websocket
I'm not a python dev but I will try to have a look...