"unused" - this field has been present in request_rec since r86043
(702dd42de, August 2000) but any use of it was removed in r86210
(5d50a3e27, September 2000) which predates any stable 2.0 release.
Done WITHOUT an MMN major bump and we could probably get away with
doing the same in 2.4.x as well (where adding fields to request_rec
breaks mod_wsgi).
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1938284 13f79535-47bb-0310-9956-ffa450edef68