Open purchase order lines are available to receive when order status is requisition

[steveblamey]

Creating a new GRN fails for order lines where order has reverted to requisition with the error 'Error creating Goods Received Note '.

Confirmed with this test case:

1. Create requisition with two lines
2. Authorise requisition
3. Receive first line
4. Cancel second line (order reverts to requisition)
5. Cancel the GRN for the first line
6. Lines still show on 'Confirm Receipt' list because they have an 'Awaiting Delivery' status.
7. Receiving first line again fails because the order type is requisition ('R')