This bug is being assigned to Bruce Reeler, who is now the designated docs specialist for Keystone.
Doc team please be aware that the above LimitRequestFieldSize setting will not resolve this issue at the moment. This issues is a hardwired limitation within the Apache function used by mod_wsgi.
This was fixed on 2014-04-04 so that the error no longer occurs: https://review.openstack.org/#/c/85147/ So the workaraound (which didnt work anyway) is not required. Seems two unnecessary fields were being included in the token which have been removed. Setting bug to closed not a bug.