indicating that the buffers sent to subscribers have to be flushed

src/ngx_http_push_stream_module_subscriber.c

@@ -413,6 +413,7 @@ ngx_http_push_stream_respond_to_subscribers(ngx_http_push_stream_channel_t *chan
             r = cur->request;
 
             r->discard_body = 0; // hacky hacky!
+            chain->buf->flush = 1;
 
             ngx_http_output_filter(r, chain);
             ngx_http_send_special(r, NGX_HTTP_FLUSH);