objgenerator.throw(): Throwing GeneratorExit is equivalent to .close().

According to PEP380 and caught by CPython test_pep380.py .

py/objgenerator.c

@@ -159,8 +159,18 @@ STATIC mp_obj_t gen_instance_send(mp_obj_t self_in, mp_obj_t send_value) {
 
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(gen_instance_send_obj, gen_instance_send);
 
+STATIC mp_obj_t gen_instance_close(mp_obj_t self_in);
 STATIC mp_obj_t gen_instance_throw(uint n_args, const mp_obj_t *args) {
-    mp_obj_t ret = gen_resume_and_raise(args[0], mp_const_none, n_args == 2 ? args[1] : args[2]);
+    mp_obj_t exc = (n_args == 2) ? args[1] : args[2];
+    if (mp_obj_is_subclass_fast(mp_obj_get_type(exc), &mp_type_GeneratorExit)) {
+        // Throwing GeneratorExit is equivalent of calling close aka
+        // GeneratorExit should be handled specially
+        // TODO: Calling .close() will throw new exception instance, not one
+        // given to throw, which is not ok.
+        return gen_instance_close(args[0]);
+    }
+
+    mp_obj_t ret = gen_resume_and_raise(args[0], mp_const_none, exc);
     if (ret == MP_OBJ_NULL) {
         nlr_jump(mp_obj_new_exception(&mp_type_StopIteration));
     } else {