core: don't break out iovec coalescing for metadata in ap_core_output_filter().
* server/core_filters.c (send_brigade_nonblocking):
Keep filling in the iovec when the next bucket has no ->length.
@@ -604,7 +604,7 @@ static apr_status_t send_brigade_nonblocking(apr_socket_t *s,
*/
if (nbytes > sconf->flush_max_threshold
&& next != APR_BRIGADE_SENTINEL(bb)
- && !is_in_memory_bucket(next)) {
+ && next->length && !is_in_memory_bucket(next)) {
(void)apr_socket_opt_set(s, APR_TCP_NOPUSH, 1);
rv = writev_nonblocking(s, bb, ctx, nbytes, nvec, c);
if (rv != APR_SUCCESS) {
