Update EDI import shipments. Some times the EDI reference is not the purchase number, it's the purchase reference, so we need to search for the reference too, ensuring is unique

shipment.py

@@ -241,6 +241,13 @@ class ShipmentIn(EdifactMixin, metaclass=PoolMeta):
                 ('number', '=', purchase_num),
                 ('state', 'in', ('processing', 'done'))
                 ], limit=1) or [None]
+        if not purchase:
+            purchases = Purchase.search([
+                    ('reference', '=', purchase_num),
+                    ('state', 'in', ('processing', 'done'))
+                    ])
+            if len(purchases) == 1:
+                purchase = purchase[0]
         if not purchase:
             error_msg = 'Purchase number {} not found'.format(purchase_num)
             serialized_segment = Serializer(control_chars).serialize([segment])