Yes. The pants unittest2 used for the test runner fully floats: https://github.com/pantsbuild/pants/blob/master/src/python/pants/backend/python/tasks/pytest_run.py#L78 So grabbing latest:

$ grep six unittest2-1.1.0/setup.py 
# six for compat helpers
REQUIRES = ['argparse', 'six>=1.4', 'traceback2'],