tls-eio: add bug note about close_notify behaviour

eio/tls_eio.ml

@@ -43,7 +43,18 @@ module Raw = struct
                as `Response resp when it encounters `close_notify` in data. *)
             if not t.close_notify_sent then begin
               Option.iter (write_t t) resp ;
-              t.close_notify_sent <- true
+              t.close_notify_sent <- true ;
+
+              (* XXX shouldn't we now close 'Send' side of flow since we are sending 
+                'close_notify' message ? lwt doesn't so we don't too and the fuzz
+                test fails if we do, so we don't too. But we really, really should shutdown
+                'Send' side of the connection here. 
+
+                TLS 1.3 [https://www.rfc-editor.org/rfc/rfc8446#section-6.1] is very specific
+                aboutt this behaviour. 
+                
+                XXX uncomment below line after discussing with @talex, @hannes. *)
+              (* Eio.Flow.shutdown t.flow `Send ; *)
             end
           | `Alert a -> raise (Tls_alert a)
         end ;