Add missing import

tests/modules/__init__.py

@@ -2,6 +2,7 @@
 from __future__ import (unicode_literals, division, absolute_import, print_function)
 
 import sys
+import os
 
 if sys.version_info < (2, 7):
 	from unittest2 import TestCase as _TestCase  # NOQA

tests/modules/lib/__init__.py

@@ -3,7 +3,6 @@ from __future__ import (unicode_literals, division, absolute_import, print_funct
 
 import imp
 import sys
-import os
 
 
 class Pl(object):