ap_content_length_filter has already set Content-Length

before ap_set_keepalive is called.  need to remove this check
in order for keepalives to work.
PR:
Obtained from:
Submitted by:
Reviewed by:


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@90700 13f79535-47bb-0310-9956-ffa450edef68