storage: Make pylint happier.

caucase/storage.py

@@ -32,6 +32,12 @@ __all__ = ('SQLite3Storage', )
 DAY_IN_SECONDS = 60 * 60 * 24
 
 class NoReentryConnection(sqlite3.Connection):
+  """
+  Refuse to start an already started transaction.
+
+  Allows detecting code bugs which would lead to non-atomic updates (partial
+  outer transaction getting committed by an inner transaction).
+  """
   __entered = False
 
   def __enter__(self):