FreeBSD erroneous Process.cpu_num()

[giampaolo]

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FAIL: psutil.tests.test_contracts.TestFetchAllProcesses.test_fetch_all
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Traceback (most recent call last):
  File "/vagrant/psutil/psutil/tests/test_contracts.py", line 340, in test_fetch_all
    meth(ret, p)
  File "/vagrant/psutil/psutil/tests/test_contracts.py", line 474, in cpu_num
    self.assertIn(ret, list(range(psutil.cpu_count())))
AssertionError: 255 not found in [0, 1]

This happens for [intr] process (with PID 12).