Code review comment for lp:~allenap/launchpad/trac-sniffing-broken-bug-504310

Pre-implementation call with Graham Binns.

Recently we've noticed that several Trac installations return HTTP 200 for page not found (i.e. should be a 404). This breaks the sniffing we do to detect the presence of the Launchpad plugin <https://launchpad.net/trac-launchpad>.

The fix proposed here is to check all HTTP 200 responses for the presence of a trac_auth cookie. This should not be present for a should-be-a-404 response. In the very very unlikely event that the authentication token we pass when sniffing (a deliberately bogus token: "check") is valid, the trac_auth cookie will be present.

I've tested this with http://trac.macports.org/ - one of the main culprits of broken 404 behaviour - and it works fine.

Lint free, other than the usual pylint nonsense.

Test: bin/test -vvt 'external.*bug'