On one of our trackers, we decided to do some
customizations to support the bigger scope of the
project. This included adding a 'category' property to
the 'issue' class. We later removed this again.
However, it did end up in the journal:

roundup-xs4all=# SELECT action, params FROM
issue__journal WHERE params LIKE '%category%';
 action |                                        params
--------+--------------------------------------------------------------------------------------
 set    | {'status': None, 'assignedto': None,
'category': None}
 set    | {'status': None, 'assignedto': None,
'category': None}

When I tried to export this tracker, I got the
following traceback:

Traceback (most recent call last):
  File
"/usr/lib/python2.3/site-packages/roundup/admin.py",
line 1273, in run_command
    ret = function(args[1:])
  File
"/usr/lib/python2.3/site-packages/roundup/admin.py",
line 1051, in do_export
    map(journals.writerow, cl.export_journals())
  File
"/usr/lib/python2.3/site-packages/roundup/backends/rdbms_common.py",
line 2508, in export_journals
    prop = properties[propname]
KeyError: 'category'

I guess export_journals shouldn't assume the property
still exists?