Merge r1442320 from trunk:

Don't keepalive the connection to the client if the
backend closes the connection.

PR: 54474
Submitted by: Pavel Mateja <pavel netsafe cz>

Submitted by: sf
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1443075 13f79535-47bb-0310-9956-ffa450edef68