Clean up breakage introduced recently that sent the wrong headers through
  the http_headers output filter.  Now we will always point every filter at
  the 'redirected' request, e.g. the actual error message response rather
  than the request that failed.

Reviewed by: JimJag, Rbb, DougM


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@94467 13f79535-47bb-0310-9956-ffa450edef68