issues.mediagoblin.org IP throttling

[Ben Sturmfels]

Hi Simon,

When submitting the form to register on issues.mediagoblin.org, I always
seem to get a message like "Maximum number of posts per hour for this IP
address exceeded", which looks to come from the Trac's "spam-filter"
plugin.

It sounded to me as though Trac might be incorrectly rate limiting based
on the proxy server's IP address, not the client's IP. I'm completely
new to haproxy, but the attached configuration change to haproxy seems
to fix the problem - this change is currently running in production.

Would you mind checking that I'm on the right track and merging if
appropriate?

Cheers,
Ben