[Xorp-hackers] Fix for PIM task list hang

[Bruce Simpson]

Thanks for the PIM patch. Unfortunately I don't have free time to look 
at this in detail at the moment.

It would be great if Pavlin were available to give it a review. PIM is 
quite a complex piece of machinery. Glancing at it, I didn't commit this 
previously, because I wasn't 100% sure about what was going on. There 
are a few practice issues in there (return from inside a switch block) 
which made me a little itchy.

Of course, I'm burning up on a task right now, so I can't really the 
patch fair consideration. +1 for 'come back to this later'.