ESI: Use response status modulo 1000

fixes https://github.com/varnishcache/varnish-cache/issues/3958

src/vdp_pesi.c

@@ -1223,6 +1223,7 @@ vped_deliver(struct req *req, struct boc *boc, int wantbody)
 	struct nexus_gzip *gz;
 	struct vped_gzgz_priv *vgzgz = NULL;
 	struct vrt_ctx ctx[1];
+	uint16_t status;
 
 	VSLdbgv(req, "vped_deliver: req=%p boc=%p wantbody=%d", req, boc,
 		wantbody);
@@ -1243,9 +1244,8 @@ vped_deliver(struct req *req, struct boc *boc, int wantbody)
 		req, boc, wantbody, pesi->pecx->incl_cont);
 	assert(parent->type == T_NEXUS);
 
-	if (!pesi->pecx->incl_cont &&
-	    req->resp->status != 200 &&
-	    req->resp->status != 204) {
+	status = req->resp->status % 1000;
+	if (!pesi->pecx->incl_cont && status != 200 && status != 204) {
 		tree_latch_error(tree, -1);
 		return;
 	}

src/vmod_pesi.man.rst

@@ -118,7 +118,7 @@ VOID activate()
 
 Enable parallel ESI processing for the client response.
 
-Restricted to: ``vcl_deliver``
+Restricted to: ``vcl_deliver``.
 
 If ``pesi.activate()`` is called on *any* ESI level (any depth of include
 nesting), then it MUST be called on *all* levels of the response. If
@@ -205,7 +205,7 @@ identified by the ENUM ``parameter``. Currently the parameters can
 only be set with a boolean value in ``bool`` (but future versions of
 this function may allow for setting other data types).
 
-Restricted to: ``vcl_deliver``
+Restricted to: ``vcl_deliver``.
 
 The parameters that can be set are currently ``serial`` and ``thread``: