I think this needs a backport to 2.7, my FreeBSD buildbots are failing on that branch since moving buildbots home directory onto a ZFS fs:

======================================================================
ERROR: test_chflags (test.test_posix.PosixTester)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/home/buildbot/python/2.7.koobs-freebsd/build/Lib/test/test_posix.py", line 350, in test_chflags
    self._test_chflags_regular_file(posix.chflags, test_support.TESTFN)
  File "/usr/home/buildbot/python/2.7.koobs-freebsd/build/Lib/test/test_posix.py", line 337, in _test_chflags_regular_file
    chflags_func(target_file, st.st_flags | stat.UF_IMMUTABLE)
OSError: [Errno 45] Operation not supported: '@test_38161_tmp'

======================================================================
ERROR: test_lchflags_regular_file (test.test_posix.PosixTester)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/home/buildbot/python/2.7.koobs-freebsd/build/Lib/test/test_posix.py", line 354, in test_lchflags_regular_file
    self._test_chflags_regular_file(posix.lchflags, test_support.TESTFN)
  File "/usr/home/buildbot/python/2.7.koobs-freebsd/build/Lib/test/test_posix.py", line 337, in _test_chflags_regular_file
    chflags_func(target_file, st.st_flags | stat.UF_IMMUTABLE)
OSError: [Errno 45] Operation not supported: '@test_38161_tmp'

----------------------------------------------------------------------
Ran 38 tests in 0.455s

I won't link the buildbot log url here since it will not be valid forever.