'cnpj_cpf' referenced before assignment

[chicocvenancio]

Em uma nova instalação estou recebendo o seguinte erro ao tentar alterar o CNPJ:

Traceback (most recent call last):
  File "/opt/odoo/OCB/openerp/http.py", line 544, in _handle_exception
    return super(JsonRequest, self)._handle_exception(exception)
  File "/opt/odoo/OCB/openerp/http.py", line 581, in dispatch
    result = self._call_function(**self.params)
  File "/opt/odoo/OCB/openerp/http.py", line 317, in _call_function
    return checked_call(self.db, *args, **kwargs)
  File "/opt/odoo/OCB/openerp/service/model.py", line 118, in wrapper
    return f(dbname, *args, **kwargs)
  File "/opt/odoo/OCB/openerp/http.py", line 314, in checked_call
    return self.endpoint(*a, **kw)
  File "/opt/odoo/OCB/openerp/http.py", line 810, in __call__
    return self.method(*args, **kw)
  File "/opt/odoo/OCB/openerp/http.py", line 410, in response_wrap
    response = f(*args, **kw)
  File "/opt/odoo/OCB/addons/web/controllers/main.py", line 944, in call_kw
    return self._call_kw(model, method, args, kwargs)
  File "/opt/odoo/OCB/addons/web/controllers/main.py", line 936, in _call_kw
    return getattr(request.registry.get(model), method)(request.cr, request.uid, *args, **kwargs)
  File "/opt/odoo/OCB/openerp/api.py", line 268, in wrapper
    return old_api(self, *args, **kwargs)
  File "/opt/odoo/OCB/openerp/api.py", line 399, in old_api
    result = method(recs, *args, **kwargs)
  File "/opt/odoo/OCB/openerp/models.py", line 6007, in onchange
    record._onchange_eval(name, field_onchange[name], result)
  File "/opt/odoo/OCB/openerp/models.py", line 5850, in _onchange_eval
    method_res = method(self)
  File "/opt/odoo/l10n-brazil/l10n_br_base/res_company.py", line 132, in onchange_mask_cnpj_cpf
    self.cnpj_cpf = cnpj_cpf
UnboundLocalError: local variable 'cnpj_cpf' referenced before assignment

Lendo o código é possível perceber que isso vai acontecer sempre que o CNPJ não possuir 14 caracteres.

Penso que precisamos de uma alternativa quando o conteúdo for diferente que 14 caracteres.