The actual error:

======================================================================
FAIL: test_exceptions_propagate (test.test_py_compile.PyCompileTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/tank/libs/cpython/Lib/test/test_py_compile.py", line 88, in test_exceptions_propagate
    py_compile.compile(self.source_path, self.pyc_path)
AssertionError: OSError not raised

----------------------------------------------------------------------
Ran 7 tests in 0.007s

FAILED (failures=1)
test test_py_compile failed
1 test failed:
    test_py_compile

os.chmod(self.directory, stat.S_IREAD) doesn't do what it is expected on FreeBSD for root user, the attached patch skips this test if the current user is root.