[FIX] sale: missing account mapping in advance invoice

The `map_account()` method expects a browse_record as
parameter, and returns a browse_record (possibly the
argument if no mapping happened).

It was being called with an account ID instead, so
fiscal position mapping would never match, and would
always return the argument itself.

addons/sale/wizard/sale_make_invoice_advance.py

@@ -65,9 +65,8 @@ def _create_invoice(self, order, so_line, amount):
         if self.product_id.id:
             account_id = self.product_id.property_account_income_id.id
         if not account_id:
-            prop = ir_property_obj.get('property_account_income_categ_id', 'product.category')
-            prop_id = prop and prop.id or False
-            account_id = order.fiscal_position_id.map_account(prop_id)
+            inc_acc = ir_property_obj.get('property_account_income_categ_id', 'product.category')
+            account_id = order.fiscal_position_id.map_account(inc_acc).id if inc_acc else False
         if not account_id:
             raise UserError(
                 _('There is no income account defined for this product: "%s". You may have to install a chart of account from Accounting app, settings menu.') % \