title: Pytest show parameter values in failure report
body: <p>Sometimes <code>pytest -vvv</code> shows the parameter values at the top of the failure report, like below, but sometimes it doesn't. How do I make it show the parameter values, when it isn't happening automatically?</p>
  
  <pre><code>=================================================================== FAILURES ===================================================================
  _____________________________________________________________ test_person[person0] _____________________________________________________________
  
  person = Person(name='Alice', hobbies=[Hobby(title='hacking')])
  
      @pytest.mark.parametrize("person", PERSONS)
      def test_person(person):
  &gt;       assert person == 'foo'
  E       AssertionError: assert Person(name='Alice', hobbies=[Hobby(title='hacking')]) == 'foo'
  
  ../../tmp/ids.py:25: AssertionError
  </code></pre>