rem: Ns_ConnSetLengthHeader(conn, length);
add: if (length >= 0) { Ns_ConnSetLengthHeader(conn, length); }
context: Ns_ConnSetRequiredHeaders(Ns_Conn *conn, char *type, int length){    Conn *connPtr = (Conn *) conn;    Ns_DString ds;    /*     * Set the standard mime and date headers.     */    Ns_DStringInit(&ds);    Ns_ConnCondSetHeaders(conn, "MIME-Version", "1.0");    Ns_ConnCondSetHeaders(conn, "Date", Ns_HttpTime(&ds, NULL));    Ns_DStringTrunc(&ds, 0);    /*     * Set the standard server header, prepending "NaviServer/2.0"     * if AOLpress support is enabled.     */    if (connPtr->servPtr->opts.aolpress) {    	Ns_DStringAppend(&ds, "NaviServer/2.0 ");    }    Ns_DStringVarAppend(&ds, Ns_InfoServerName(), "/", Ns_InfoServerVersion(), NULL);    Ns_ConnCondSetHeaders(conn, "Server", ds.string);    /*     * Set the type and/or length headers if provided.  Note     * that a valid length is required for connection keep-alive.     */    if (type != NULL) {    	Ns_ConnSetTypeHeader(conn, type);    }    Ns_ConnSetLengthHeader(conn, length);    Ns_DStringFree(&ds);}