I also note *one* failure on koobs-freebsd-9 on 3.x and 3.6 branches, identical errors:

Nov 09 14:53 c27269c0d619... failure AMD64 FreeBSD 9.x 3.x #5304 Failed test
Nov 09 14:53 b671ac7ae620... failure AMD64 FreeBSD 9.x 3.6 #282  Failed test

======================================================================
ERROR: test_chown (test.test_os.ChownFileTests)
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Traceback (most recent call last):
  File "/usr/home/buildbot/python/3.6.koobs-freebsd9/build/Lib/test/test_os.py", line 1200, in test_chown
    os.chown(support.TESTFN, uid, gid_1)
PermissionError: [Errno 1] Operation not permitted: '@test_83654_tmp'

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======================================================================
ERROR: test_chown (test.test_os.ChownFileTests)
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Traceback (most recent call last):
  File "/usr/home/buildbot/python/3.x.koobs-freebsd9/build/Lib/test/test_os.py", line 1200, in test_chown
    os.chown(support.TESTFN, uid, gid_1)
PermissionError: [Errno 1] Operation not permitted: '@test_93884_tmp'

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I cannot explain what would cause persistent failure on one host and intermittent failure on another, except perhaps different host resources (cpu/mem) creating favourable conditions on one, but not the other.