Status: the "last_in_chain" flag must be set.

The module always produces only one and obviously the last buffer in chain.
diff --git a/src/http/modules/ngx_http_stub_status_module.c b/src/http/modules/ngx_http_stub_status_module.c
index 83a35cd..fe9132d 100644
--- a/src/http/modules/ngx_http_stub_status_module.c
+++ b/src/http/modules/ngx_http_stub_status_module.c
@@ -145,6 +145,7 @@
     r->headers_out.content_length_n = b->last - b->pos;
 
     b->last_buf = (r == r->main) ? 1 : 0;
+    b->last_in_chain = 1;
 
     rc = ngx_http_send_header(r);