Several tests fail on Python 3 with TypeError: unorderable types: str() < int()

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ERROR: test_remove_duplicates (apache_beam.transforms.ptransform_test.PTransformTest)
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Traceback (most recent call last):
File "/usr/local/google/home/valentyn/projects/beam/clean_head/beam/sdks/python/apache_beam/runners/common.py", line 677, in process
self.do_fn_invoker.invoke_process(windowed_value)
File "/usr/local/google/home/valentyn/projects/beam/clean_head/beam/sdks/python/apache_beam/runners/common.py", line 414, in invoke_process
windowed_value, self.process_method(windowed_value.value))
File "/usr/local/google/home/valentyn/projects/beam/clean_head/beam/sdks/python/apache_beam/transforms/core.py", line 1068, in <lambda>
wrapper = lambda x: [fn(x)]
File "/usr/local/google/home/valentyn/projects/beam/clean_head/beam/sdks/python/apache_beam/testing/util.py", line 115, in _equal
sorted_expected = sorted(expected)
TypeError: unorderable types: str() < int()