Why doesn't uWSGI listen on IPv6 interface, even if system is 100% IPv6 ready? As far as I could see there aren't parameters nor documentation covering this issue.
In your INI config file specify something like this 
[uwsgi]
socket = [::]:your_port_number
Or from the CL, 
./uwsgi -s [::]:your_port_number
The server shall now listen along all the interfaces (including IPv4, if the underlying OS supports dual stack TCP sockets)
uWSGI --http :80 doesn't listen IPv6 interface