Change id to return signed integer.

py/builtin.c

@@ -366,7 +366,7 @@ static mp_obj_t mp_builtin_bytes(uint n_args, const mp_obj_t *args) {
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_builtin_bytes_obj, 1, 3, mp_builtin_bytes);
 
 static mp_obj_t mp_builtin_id(mp_obj_t o_in) {
-    return mp_obj_new_int_from_uint((machine_uint_t)o_in);
+    return mp_obj_new_int((machine_int_t)o_in);
 }
 
 MP_DEFINE_CONST_FUN_OBJ_1(mp_builtin_id_obj, mp_builtin_id);

tests/basics/builtin_id.py

 print(id(1) == id(2))
 print(id(None) == id(None))
+print(id([]) == id([]))
+
+l = [1, 2]
+print(id(l) == id(l))
+
+f = lambda:None
+print(id(f) == id(f))