[iter] exhaust ListIterator when unpack_var_sequence is called (pytorch#156370)

Pull Request resolved: pytorch#156370
Approved by: https://github.com/zou3519
ghstack dependencies: pytorch#156369

Author: Guilherme Leobas

test/dynamo_expected_failures/CPython313-test_iter-TestCase.test_sinkstate_dict

@@ -1279,8 +1279,13 @@ def as_python_constant(self):
             raise NotImplementedError
         return iter([x.as_python_constant() for x in self.items])
 
+    def has_unpack_var_sequence(self, tx):
+        return True
+
     def unpack_var_sequence(self, tx):
-        return list(self.items[self.index :])
+        r = list(self.items[self.index :])
+        self.index = len(self.items)
+        return r
 
     def force_unpack_var_sequence(self, tx) -> list[VariableTracker]:
         return self.unpack_var_sequence(tx)