We've got a partially hosed hyperdb with broken
link entries. At the moment I'm just hunting for busted
entries manually - it would be nice if there was a 
simple tool that walked the hyperdb looking for 
problems.

While I feel your pain Anthony, I doubt this is going to happen.
I am closing it as won't fix.

If I had to do this, I would probably use the roundup_admin interface
to dump with the -d and -S , options so I could get:

   % for issue in `roundup_admin.py -i demo -s -d list issue`; do
         for users in `roundup_admin.py -i demo -s -d get assignedto
issue$i`
         roundup_admin.py -i demo > /dev/null || echo $user is missing

etc.

Also I am not sure if an export would help there may be errors reported
as a result of that that will let you discover missing links.