Merge r1557320 from trunk:

 * r1557320
   Resolve segfault while handling OPTIONS request in unusual server
   configuration.
   Justification:
     User triggerable segfaults are bad.
   Votes:
     +1: breser, rhuijben, stefan2


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/1.8.x@1558292 13f79535-47bb-0310-9956-ffa450edef68