r1469 merge:

read EOF of header only responses in non-buffered proxying

src/http/ngx_http_upstream.c

@@ -1488,6 +1488,11 @@ ngx_http_upstream_send_response(ngx_http_request_t *r, ngx_http_upstream_t *u)
                 ngx_http_upstream_finalize_request(r, u, 0);
                 return;
             }
+
+            if (u->peer.connection->read->ready) {
+                ngx_http_upstream_process_non_buffered_body(
+                                                     u->peer.connection->read);
+            }
         }
 
         return;