If the currency rate has changed on a foreign currency invoice during the time when the goods are delivered (receipt) and the invoice the accounting gets messed up and the difference multipled by the foreign currency rate is accounted on the suspense account.
How to reproduce bug:
* Create a purchase order in a currency different (currency X) from the accounting currency.
* Set the currency rate for currency X.
* Create a receipt for the purchase order.
* Change the currency rate for currency X to be different than the rate on the receipt.
* Create an invoice on the new date with the new rate.
* Match the receipt and the invoice line.
* Check the accounting of the MatchInv. It will be very wrong.