Description:
------------
Please try to run the following code. As result the following error will be displayed:
"Fatal error: Class 'Monolog\Handler\MailHandler' not found in /home/user/project/test/index.php on line 6"

If you will try to remove the " extends AbstractProcessingHandler" part the error will not be displayed.

This error prevents us to combine multiple classes to single file for performance optimization.

Test script:
---------------
<?php
namespace My\Logger {
    use Monolog\Handler\MailHandler as BaseMailHandler;

    class MailHandler extends BaseMailHandler
    {
    }
}
namespace Monolog\Handler {
    abstract class MailHandler extends AbstractProcessingHandler
    {
    }
}
namespace Monolog\Handler {
    abstract class AbstractProcessingHandler
    {
    }
}


Expected result:
----------------
No error

Actual result:
--------------
Fatal error: Class 'Monolog\Handler\MailHandler' not found in /home/user/project/test/index.php on line 6