title: pytest fixture yield list of dict throws "yield_fixture function has more than one 'yield':"
body: <p>I have defined a fixture like :</p>
  
  <pre><code>    @pytest.fixture
      def mock_yield_data(self):
          for data in [
              {
                  1: 2, 2: 3
              },
              {
                  2: 4, 4: 5
              },
          ]:
              yield data
  </code></pre>
  
  <p>and a test method like :</p>
  
  <pre><code>    def test_fixture(self, mock_yield_data):
          for data in mock_yield_data:
              assert data
  </code></pre>
  
  <p>The assert is successful but the <code>teardown</code> throws, <code>yield_fixture function has more than one 'yield':</code>.</p>
  
  <pre><code>==================================================================================================== ERRORS ====================================================================================================
  _________________________________________________________________________ ERROR at teardown of TestClass.test_fixture _________________________________________________________________________
  yield_fixture function has more than one 'yield':
  </code></pre>