Clean up pylint errors in top-level files

Change-Id: Ida7cf1ff0cbf94ad82c7a75708c79ad7bb27f7fd

nova/exception.py

@@ -24,10 +24,10 @@ SHOULD include dedicated exception logging.
 
 """
 
-from functools import wraps
+import functools
 import sys
 
-from novaclient import exceptions as novaclient_exceptions
+import novaclient.exceptions
 import webob.exc
 
 from nova import log as logging
@@ -51,7 +51,7 @@ def novaclient_converter(f):
         try:
             ret = f(*args, **kwargs)
             return ret
-        except novaclient_exceptions.ClientException, e:
+        except novaclient.exceptions.ClientException, e:
             raise ConvertedException(e.code, e.message, e.details)
     return new_f
 
@@ -156,7 +156,7 @@ def wrap_exception(notifier=None, publisher_id=None, event_type=None,
                 # re-raise original exception since it may have been clobbered
                 raise exc_info[0], exc_info[1], exc_info[2]
 
-        return wraps(f)(wrapped)
+        return functools.wraps(f)(wrapped)
     return inner