It seems there is a sporadic failure on OS X (oops, sorry, I mean "macOS"):

https://travis-ci.org/python/cpython/jobs/248079407#L3403

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FAIL: test_getsitepackages (test.test_site.HelperFunctionsTests)

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Traceback (most recent call last):

  File "/Users/travis/build/python/cpython/Lib/test/test_site.py", line 266, in test_getsitepackages

    self.assertEqual(len(dirs), 2)

AssertionError: 1 != 2

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