stream may be absent
We have seen these errors:
ERROR:tornado.general:Attempted to attach to session 7ceo057h (::1) from different IP (127.0.0.1)
ERROR:tornado.general:Attempted to attach to session 60qsy81d (127.0.0.1) from different IP (::1)
Normalize the ipv6 to ipv4 expression of localhost.
Merge branch 'nostreamerror' of https://github.com/maparent/sockjs-tornado