[7.0] base_custom_attributes - openerp-server revno 5107 breaks product attribute selection field

[Yannick Vaucher @ Camptocamp]

Since
http://bazaar.launchpad.net/~openerp/openobject-server/7.0/revision/5107

(In ocb-server http://bazaar.launchpad.net/~ocb/ocb-server/7.0/revision/5125)

This fix breaks the selection field as it impossible to create attribute options anymore

Create a product attribute
- name: x_country_id
- type: select
- model: res.country
- domain: []

Click on Load Options
Add Åland Islands
Validate

It will generate the following error when trying to generate the options:

---------------
ValidateError

The value "res.country,16" for the field "attribute_option.value_ref" is not in the selection
---------------

This is due to some creation of an empty list for valid values in selection.