[FIX] account_payment: amount in payment order is not correct.

Amount in payment order is not correct if the account move
line has already been paid by another way. The right amount is
in the residual field related with move_id to the account invoice.

opw:628903, 628428

addons/account_payment/account_move_line.py

@@ -31,21 +31,15 @@ class account_move_line(osv.osv):
         (excepting cancelled orders)"""
         if not ids:
             return {}
+        res = dict.fromkeys(ids, 0.0)
         cr.execute("""SELECT ml.id,
-                    CASE WHEN ml.amount_currency < 0
-                        THEN - ml.amount_currency
-                        ELSE ml.credit
-                    END -
-                    (SELECT coalesce(sum(amount_currency),0)
-                        FROM payment_line pl
-                            INNER JOIN payment_order po
-                                ON (pl.order_id = po.id)
-                        WHERE move_line_id = ml.id
-                        AND po.state != 'cancel') AS amount
+                    (SELECT sum(coalesce(residual, 0))
+                        FROM account_invoice
+                        WHERE move_id = ml.move_id)
                     FROM account_move_line ml
                     WHERE id IN %s""", (tuple(ids),))
-        r = dict(cr.fetchall())
-        return r
+        res.update(cr.fetchall())
+        return res
 
     def _to_pay_search(self, cr, uid, obj, name, args, context=None):
         if not args: