Backport r821477 from trunk:

    Make sure to not destroy bucket brigades that have been created by earlier
    filters. Otherwise the pool cleanups would be removed causing potential
    memory leaks later on.

Submitted by: Stefan Fritsch
Reviewed by: sf, rpluem, pgollucci


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@916627 13f79535-47bb-0310-9956-ffa450edef68