pickle and __slots__

[JL]

>     Is this a subclass?  Look at the parent classes.

Its class is a subclass of a similar class, but it indirectly
references instances of subclasses of asyncore.dispatcher or
asynchat.async_chat. I don't think there are other particular classes.
If I remove the first references, pickle works. Anyway it seems that I
will have to mask the asyncore.dispatcher and asynchat.async_chat
subclass instances which will not be relevant at unpickle time.