minor fix in serial no
diff --git a/erpnext/stock/doctype/serial_no/serial_no.py b/erpnext/stock/doctype/serial_no/serial_no.py
index df5e194..19fb033 100644
--- a/erpnext/stock/doctype/serial_no/serial_no.py
+++ b/erpnext/stock/doctype/serial_no/serial_no.py
@@ -280,6 +280,7 @@
 	sr = frappe.new_bean("Serial No")
 	sr.doc.serial_no = serial_no
 	sr.doc.item_code = sle.item_code
+	sr.doc.warehouse = None
 	sr.make_controller().via_stock_ledger = True
 	sr.insert()
 	sr.doc.warehouse = sle.warehouse