minor fix in old patch
diff --git a/erpnext/patches/v8_1/set_delivery_date_in_so_item.py b/erpnext/patches/v8_1/set_delivery_date_in_so_item.py
index aa5cbc5..e3e23a5 100644
--- a/erpnext/patches/v8_1/set_delivery_date_in_so_item.py
+++ b/erpnext/patches/v8_1/set_delivery_date_in_so_item.py
@@ -13,11 +13,11 @@
frappe.db.sql("""
update `tabSales Order` so, `tabSales Order Item` so_item
- set so_item.delivery_date = so.delivery_date
+ set so_item.delivery_date = if(ifnull(so.delivery_date, '0000-00-00'), ifnull(so.delivery_date, '0000-00-00'), '0000-00-00')
where so.name = so_item.parent
and so.order_type = 'Sales'
and (so_item.delivery_date is null or so_item.delivery_date = ''
or so_item.delivery_date = '0000-00-00')
- and (so.delivery_date is not null and so.delivery_date != ''
+ and (so.delivery_date is not null and so.delivery_date != '' and so.delivery_date != ""
and so.delivery_date != '0000-00-00')
""")