See the patch I attached to
http://nagoya.apache.org/bugzilla/show_bug.cgi?id=15423.
ap_internal_fast_redirect() has the logic I added to
internal_internal_redirect() as well as another check.
If anybody recalls the details of the ap_internal_fast_redirect()
handling of the subrequest filter (particularly the "else if") you might
as well look at it now rather than after I break the server :)
