explain the last change

account_statement_ext/statement.py

@@ -656,6 +656,9 @@ class AccountBankSatementLine(Model):
         if partner_id:
             part = obj_partner.browse(cr, uid, partner_id, context=context)
             part = part.commercial_partner_id
+            # When the method is called from bank statement completion,
+            # ensure that the line's partner is a commercial
+            # (accounting) entity
             res['partner_id'] = part.id
             pay_account = part.property_account_payable.id
             receiv_account = part.property_account_receivable.id