mod_proxy hangs when both KeepAlive and ProxyErrorOverride are enabled,

and a non-200 response without a body is generated by the backend
server.

Submitted by: Graham Wiseman, Richard Reiner
Reviewed by: Richard Reiner, Bill Stoddard


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@102239 13f79535-47bb-0310-9956-ffa450edef68