Merge r1307394 from trunk:

PR37194: give a hint about capturing something more like "initial" header
values when a %{foo}i might have been set or changed by a module.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1307396 13f79535-47bb-0310-9956-ffa450edef68