[FIX] hr_holidays: make action_approve really work in batch

addons/hr_holidays/models/hr_holidays.py

@@ -434,14 +434,12 @@ class Holidays(models.Model):
         self._check_security_action_approve()
 
         current_employee = self.env['hr.employee'].search([('user_id', '=', self.env.uid)], limit=1)
-        for holiday in self:
-            if holiday.state != 'confirm':
-                raise UserError(_('Leave request must be confirmed ("To Approve") in order to approve it.'))
+        if any(holiday.state != 'confirm' for holiday in self):
+            raise UserError(_('Leave request must be confirmed ("To Approve") in order to approve it.'))
 
-            if holiday.double_validation:
-                return holiday.write({'state': 'validate1', 'first_approver_id': current_employee.id})
-            else:
-                holiday.action_validate()
+        self.filtered(lambda hol: hol.double_validation).write({'state': 'validate1', 'first_approver_id': current_employee.id})
+        self.filtered(lambda hol: not hol.double_validation).action_validate()
+        return True
 
     @api.multi
     def _prepare_create_by_category(self, employee):