Fixed missing import of os

fs/base.py

@@ -20,6 +20,7 @@ __all__ = ['DummyLock',
            'flags_to_mode',
            'NoDefaultMeta']
 
+import os
 import os.path
 import shutil
 import fnmatch

fs/s3fs.py

@@ -9,6 +9,7 @@ interface for objects stored in Amazon Simple Storage Service (S3).
 
 """
 
+import os
 import datetime
 import tempfile
 from fnmatch import fnmatch