ensemble.formula.tests.test_bundle.BundleTest.test_executable_extraction fails on empty home dir

This is the last test failing on buildd's as of trunk revision 336 + the two fixes already submitted for review.

[FAIL]
Traceback (most recent call last):
  File "/build/buildd/ensemble-0.5+bzr336/ensemble/lib/mocker.py", line 146, in test_method_wrapper
    result = test_method()
  File "/build/buildd/ensemble-0.5+bzr336/ensemble/formula/tests/test_bundle.py", line 89, in test_executable_extraction
    self.assertEqual(stat.S_IMODE(os.stat(hook_path)[0]), 493)
twisted.trial.unittest.FailTest: not equal:
a = 509
b = 493

ensemble.formula.tests.test_bundle.BundleTest.test_executable_extraction
-------------------------------------------------------------------------------
Ran 1428 tests in 154.169s

FAILED (failures=1, successes=1427)