read EOF of header only responses in non-buffered proxying

src/http/ngx_http_upstream.c

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index fa84772..650c84c 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -1490,6 +1490,11 @@
                 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;