Python PreCommit flaking in PipelineOptionsTest.test_display_data

self = <apache_beam.options.pipeline_options_test.PipelineOptionsTest testMethod=test_display_data>

    def test_display_data(self):
      for case in PipelineOptionsTest.TEST_CASES:
        options = PipelineOptions(flags=case['flags'])
        dd = DisplayData.create_from(options)
>       hc.assert_that(dd.items, hc.contains_inanyorder(*case['display_data']))

apache_beam/options/pipeline_options_test.py:222: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
target/.tox-py36-cloud/py36-cloud/lib/python3.6/site-packages/hamcrest/library/collection/issequence_containinginanyorder.py:68: in describe_mismatch
    self.matches(item, mismatch_description)
target/.tox-py36-cloud/py36-cloud/lib/python3.6/site-packages/hamcrest/library/collection/issequence_containinginanyorder.py:64: in matches
    .describe_mismatch(sequence, mismatch_description)
target/.tox-py36-cloud/py36-cloud/lib/python3.6/site-packages/hamcrest/core/base_matcher.py:34: in describe_mismatch
    mismatch_description.append_text('was ').append_description_of(item)
target/.tox-py36-cloud/py36-cloud/lib/python3.6/site-packages/hamcrest/core/base_description.py:34: in append_description_of
    description = str(value)
apache_beam/transforms/display.py:359: in __repr__
    return 'DisplayDataItem({})'.format(json.dumps(self._get_dict()))
/usr/lib/python3.6/json/__init__.py:231: in dumps
    return _default_encoder.encode(obj)
/usr/lib/python3.6/json/encoder.py:199: in encode
    chunks = self.iterencode(o, _one_shot=True)
/usr/lib/python3.6/json/encoder.py:257: in iterencode
    return _iterencode(o, 0)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <json.encoder.JSONEncoder object at 0x7fef54dd19b0>
o = <apache_beam.options.value_provider.RuntimeValueProvider object at 0x7feeb2ed5c50>

    def default(self, o):
        """Implement this method in a subclass such that it returns
        a serializable object for ``o``, or calls the base implementation
        (to raise a ``TypeError``).
    
        For example, to support arbitrary iterators, you could
        implement default like this::
    
            def default(self, o):
                try:
                    iterable = iter(o)
                except TypeError:
                    pass
                else:
                    return list(iterable)
                # Let the base class default method raise the TypeError
                return JSONEncoder.default(self, o)
    
        """
        raise TypeError("Object of type '%s' is not JSON serializable" %
>                       o.__class__.__name__)
E       TypeError: Object of type 'RuntimeValueProvider' is not JSON serializable

/usr/lib/python3.6/json/encoder.py:180: TypeError