esi nexuses have their own gzip context

using the paren't was wong

src/vdp_pesi.c

@@ -2792,7 +2792,7 @@ vped_deliver(struct req *req, struct boc *boc, int wantbody)
 	VSLdbg(req, "vped_deliver: ESI");
 
 	VDP_Push(req, &VDP_pesi_buf, pesi);
-	AZ(push_vdps(req, &parent->nexus.gzip));
+	AZ(push_vdps(req, &node->nexus.gzip));
 	AN(parent);
 	AZ(VDP_Push(req, &vped_to_parent, parent->nexus.req));