cannot merge lead in opportunity by merging both opportunities

- create one lead with a partner name
- convert it into opportyunity by creating a new partner
- create a second lead and link it to the partner you have just created
- convert this ead to opportunities.

the popup propose you to merge both opportunities. Click create opportunity :

Client Traceback (most recent call last):
  File "/home/aline/openerp/web/openerp-web/addons/web/common/dispatch.py", line 169, in dispatch
    response["result"] = method(controller, self, **self.params)
  File "/home/aline/openerp/web/openerp-web/addons/web/controllers/main.py", line 733, in call_button
    action = self.call_common(req, model, method, args, domain_id, context_id)
  File "/home/aline/openerp/web/openerp-web/addons/web/controllers/main.py", line 725, in call_common
    return getattr(req.session.model(model), method)(*args)
  File "/home/aline/openerp/web/openerp-web/addons/web/common/openerplib/main.py", line 339, in proxy
    *args)
  File "/home/aline/openerp/web/openerp-web/addons/web/common/openerplib/main.py", line 216, in proxy
    result = self.connector.send(self.service_name, method, *args)
  File "/home/aline/openerp/web/openerp-web/addons/web/common/openerplib/main.py", line 93, in send
    return getattr(service, method)(*args)
  File "/usr/lib/python2.6/xmlrpclib.py", line 1199, in __call__
    return self.__send(self.__name, args)
  File "/usr/lib/python2.6/xmlrpclib.py", line 1489, in __request
    verbose=self.__verbose
  File "/usr/lib/python2.6/xmlrpclib.py", line 1253, in request
    return self._parse_response(h.getfile(), sock)
  File "/usr/lib/python2.6/xmlrpclib.py", line 1392, in _parse_response
    return u.close()
  File "/usr/lib/python2.6/xmlrpclib.py", line 838, in close
    raise Fault(**self._stack[0])

Server Traceback (most recent call last):
  File "/home/aline/openerp/server/trunk/openerp/netsvc.py", line 440, in dispatch
    result = ExportService.getService(service_name).dispatch(method, auth, params)
  File "/home/aline/openerp/server/trunk/openerp/service/web_services.py", line 583, in dispatch
    res = fn(db, uid, *params)
  File "/home/aline/openerp/server/trunk/openerp/osv/osv.py", line 118, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/home/aline/openerp/server/trunk/openerp/osv/osv.py", line 172, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/home/aline/openerp/server/trunk/openerp/osv/osv.py", line 163, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/home/aline/openerp/addons/trunk/crm/wizard/crm_lead_to_opportunity.py", line 213, in action_apply
    return merge_obj.merge(cr, uid, data.opportunity_ids, context=context)
  File "/home/aline/openerp/addons/trunk/crm/wizard/crm_merge_opportunities.py", line 145, in merge
    message_obj.write(cr, uid, history.id, {'res_id': first_opportunity.id, 'name' : _("From %s : %s") % (opp.name, history.name) }, context=context)
  File "/home/aline/openerp/server/trunk/openerp/osv/orm.py", line 447, in __getattr__
    raise AttributeError(e)
AttributeError: "Field 'name' does not exist in object 'browse_record(mail.message, 5)'"