`php artisan down` throws uncaught 503 and yields an error page - php

Question

Edit: Accepted Issue on GitHub https://github.com/octobercms/october/issues/2830
I am using OctoberCMS which is based upon the Laravel PHP framework.
(I am a newbie to both).
Ultimately, I'm trying to script as much of the site update process as possible. That is, update/upgrade the testing and live sites and upload my new code. This entails being able to put the site into maintenance mode from the command line.
The top level directory for my website (/var/www/website/) contains the artisan php script.
Running php artisan list I get:
Available commands:
down Put the application into maintenance mode
up Bring the application out of maintenance mode
Within the OctoberCMS backend I can put the frontend into maintenance mode, and the chosen maintenance page is shown as expected.
When I enter php artisan down in the console I get Application is now in maintenance mode., as expected. But when I reload the website, I get the following error:
We're sorry, but an unhandled error occurred. Please see the details below.
.../vendor/laravel/framework/src/Illuminate/Foundation/Http/Middleware/CheckForMaintenanceMode.php line 41
Type: Undefined
Exception: Symfony\Component\HttpKernel\Exception\HttpException
\*
\* #throws \Symfony\Component\HttpKernel\Exception\HttpException
*/
public function handle($request, Closure $next)
{
if ($this->app->isDownForMaintenance()) {
throw new HttpException(503);
}
return $next($request);
}
It would appear that Laravel/Symfony is doing what it should and throwing a 503 Service Unavailable, but there is nothing to catch it and render the maintenance page.
So, two questions
1) Is this a bug? If so, in Laravel or October? Or have I done something wrong -- config setting...?
2) Assuming it won't be 'fixed' any time soon, how and where should I catch the HttpException(503) and yield the maintenance page?
There is what might be an answer in Stackoverflow > '503 can't be overridden in L5.1', which appears to suggest editing/overriding public function handle($request, Closure $next) with a try/catch/return-if-503 sequence. But is it a good idea to override a function of the CMS/framework? If so, how and where?
I have read OctoberCMS > docs > services > Errors & Logging and, despite hoping for an easier solution, I would create a Plugin to solve the problem if that is the best/only/ideal way. Although creating a Plugin to catch what should surely already be caught seems overkill.
This looks to be the way to do it Laravel - Pass arguments to php artisan down, but I'm not confident to attempt it.
Turnkey LAMP 14.1 server
October system build 414
php --version
PHP 5.6.30-0+deb8u1 (cli) (built: Feb 8 2017 08:50:21)
php artisan --version
Laravel Framework version 5.1.46 (LTS)