This is not a complete patch.  I've worked on it for
the rdbms section but nothing else.  In our tracker, we
wanted the user's realname to show when possible.  So
we added a labelprop to the realname.  That seemed to
work fine at first.  The problem is that the user is a
Multilink in the nosy list.  So when the nosy list is
being displayed it is showing the realnames.  That in
itself is ok, but if you make any changes, it tries to
find the realnames.  What I did was create a new
function that is similar to lookup but uses the
labelprop instead of a key.  This new function I called
llookup.  I added a stub function in hyperdb.py and the
good function in rdbms_common.py.  I then modified the
KeyError in hyperdb.py to see if there is a labelprop.
 If there is, I call the llookup to find the row based
on the labelprop.  If it can't find it or there isn't a
labelprop, it then gives the KeyError.

As stated before, I did not make the necessary changes
anywhere but in the rdbms_common.py and hyperdb.py. 
back_anydbm.py and back_metakit.py would still need to
be changed.

My email is:
David.Byrne@cambridge-na.com

Thanks,
David Byrne