[FIX] point of sale: Closing a cash control session

Before the fix:
When creating a new session with Cash control POS then it was impossible to close the session.

After the fix:
The same flow as in 9.0 when closing a session

opw:691517

addons/point_of_sale/models/pos_session.py

@@ -223,6 +223,10 @@ class PosSession(models.Model):
     @api.multi
     def action_pos_session_closing_control(self):
         for session in self:
+            #DO NOT FORWARD-PORT
+            if session.state == 'closing_control':
+                session.action_pos_session_close()
+                continue
             for statement in session.statement_ids:
                 if (statement != session.cash_register_id) and (statement.balance_end != statement.balance_end_real):
                     statement.write({'balance_end_real': statement.balance_end})