We have seen cases where verify_ip fails on ipv4 vs ipv6 expression of localhost

Eg from our stderr:
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)
I do a simple normalization to the ipv4 version: I'm sure something smarter could be done.
This is at least a way to pinpoint the issue.