title: Python 3.7: Inheriting list, abstract ignored
body: <p>The following does not raise:</p>
  
  <pre><code>from abc import ABCMeta, abstractmethod
  class Test(list, metaclass=ABCMeta):
      @abstractmethod
      def test(self):
          pass
  test = Test()
  </code></pre>
  
  <p>although this does:</p>
  
  <pre><code>from abc import ABCMeta, abstractmethod
  class Test(metaclass=ABCMeta):
      @abstractmethod
      def test(self):
          pass
  test = Test()
  </code></pre>
  
  <p>Is this a known problem? What can I do to fix it? I need to inherit from something that looks exactly like a list and create an abstract inheritor. Thank you.</p>