Bug with tax line computing

In the file account/invoice.py, two functions of the class "account_invoice_tax" are returning the ID of the company instead of the ID of the currency.
The two function are: base_change( ... ) and amount_change( ... )
In both functions, the line:
    company_currency=company_obj.browse(cr,uid,company_id).id
should be replaced by:
    company_currency=company_obj.browse(cr,uid,company_id).currency_id.id

Not doing this change results in having a result amount computed with the wrong currency object in the case where the ID of the company not being the same as the company's currency object

Best regards