[Mailman-Users] preserving original lists' subject prefix

[Raymond Blum]

Hi all
  I have a situation where I need to preserve the "history" or chain of
subscriptions that a message has passed through on its way to the
recipients.  For example if user1 subscribes to list1 and list1 is
subscribed to list2, I wish messages sent to list2 to have something like
this in the subject

[List1] [List2] here is a message for you

It looks like mailman is removing [List2], leaving me with [List1] ... as
the subject.  If empty out the subject prefix for List1, then neither
appears.

Is there a way to do this?  I was surprised to see that Mailman was
rewriting the subject, rather than just prefacing it.

Thanks
---Raymond