[FIX] purchase: taxes from PO

If a user removes the taxes on a PO line, the product taxes will be
added back when the invoice is created.

opw-676858

addons/purchase/invoice.py

@@ -49,7 +49,7 @@ class AccountInvoice(models.Model):
                 qty = line.qty_received - line.qty_invoiced
             if float_compare(qty, 0.0, precision_rounding=line.product_uom.rounding) <= 0:
                 qty = 0.0
-            taxes = line.taxes_id or line.product_id.supplier_taxes_id
+            taxes = line.taxes_id
             invoice_line_tax_ids = self.purchase_id.fiscal_position_id.map_tax(taxes)
             data = {
                 'purchase_line_id': line.id,