Fixed: Update purchase failed when date was changed

Signed-off-by: Amritanshu <tanshu@gmail.com>

brewman/views/services/voucher/purchase.py

@@ -105,7 +105,7 @@ def purchase_update_inventory(voucher, newInventories):
                 tax = round(Decimal(i['Tax']), 5)
                 if voucher.date != item.batch.name:
                     item.batch.name = voucher.date
-                    if voucher.date < item.batch.date:
+                    if voucher.date < item.batch.name:
                     # TODO: check for issued products which might have been in a back date
                         pass
                 item.rate = rate