Fix a bug which would cause the response headers to be omitted

when sending a negotiated ErrorDocument because the required
filters were attached to the wrong request_rec.

Submitted by:	John Sterling <sterling@covalent.net>
Reviewed by:	Justin Erenkrantz, Cliff Woolley


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@91900 13f79535-47bb-0310-9956-ffa450edef68