Ticket #2576: Can't test complex parameters.

Hi.

Will someone please review and apply the patch in this comment.
https://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/2576-integration-test-fails-on-complex-forms-updating-multiple-models#ticket-2576-12

Joshua claims it is fixed in edge (I have not verified this). However
it is a still an annoying bug in 2.3 branch. I have now made a patch
against the 2-3-stable branch including two unit tests that
demonstrates the problem.

Will someone please apply this patch to the 2-3-stable branch, so that the next 2.3.x release
does not include this bug.

Jarl