bug with the "lead converted into opportunity" log

In web trunk (tested with firefox)

steps to reproduce
- create a lead
- convert it into opportunity
- 2 logs are created
- click the second log (the lead xxx has been converted into opportunity)
- Bug

Traceback (most recent call last):
  File "/home/aline/openerp/trunk/server/bin/netsvc.py", line 489, in dispatch
    result = ExportService.getService(service_name).dispatch(method, auth, params)
  File "/home/aline/openerp/trunk/server/bin/service/web_services.py", line 598, in dispatch
    res = fn(db, uid, *params)
  File "/home/aline/openerp/trunk/server/bin/osv/osv.py", line 122, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/home/aline/openerp/trunk/server/bin/osv/osv.py", line 176, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/home/aline/openerp/trunk/server/bin/osv/osv.py", line 167, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/home/aline/openerp/trunk/server/bin/osv/orm.py", line 2077, in read
    res2 = self._columns[f].get_memory(cr, self, ids, f, user, context=context, values=result)
  File "/home/aline/openerp/trunk/server/bin/osv/fields.py", line 340, in get_memory
    result[id] = obj.datas[id].get(name, False)
KeyError: 9