py3.5 travis tests fail non-deterministically

[szagoruyko]

very odd, sometimes py3.5 bugs out on splitdataset, 3.6 is fine:

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FAIL: testSplitDataset (__main__.TestDatasets)
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Traceback (most recent call last):
  File "test_datasets.py", line 102, in testSplitDataset
    self.assertEqual(splitdataset[2], 2)
AssertionError: 3 != 2

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FAIL: testSplitDataset_fractions (__main__.TestDatasets)
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Traceback (most recent call last):
  File "test_datasets.py", line 122, in testSplitDataset_fractions
    self.assertEqual(splitdataset[2], 2)
AssertionError: 3 != 2

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Ran 10 tests in 0.003s