Error replies were crashing with NullPointerException while checking
if the request method was HEAD. Some error paths do not pass in the
HttpServletRequest, which means the response code cannot check and
avoid writing the body.
Pass in the request in one more location, and assume the body must
be written if the request was not supplied. The servlet container
should gracefully discard the body if the request really was HEAD.
Change-Id: I8f0daf06727fd94c4be4d9d8019686ee4c1bac17
e40b1a436b