Renaming fields in Openerp

Fields are not handeled correctly when renamed.

1. Create an object "x_product_category" with a field x_name and a field x_code
2. Create an object "x_product" with a field x_name and a field x_category as many2one with a rel object "x_product_category" and should be required
3. Create an a product category
4. Create a product
5. Rename the field x_category in step 2 to x_category_id
4. Create a new product.

You will get a warning that the field x_category can not be empty.

This behaviour is due to the fact that Openerp did create a second column in the x_product table with the name x_category_id instead of renaming the first one.