The clusterpurge.php script does not delete expired items that are in the scope 'images' on the 'ezdfsfile' table; it only clears items for the scope 'image'.

Steps to reproduce:

1. Configure eZP 5.2 in DFS cluster mode;
2. Create an object with an image;
3. Publish some versions;
4. Query 'ezdfsfile' table, and make a note of what records exist for "scope=images" and "expired=1". The following query should suffice:

SELECT name, datatype, scope, expired FROM ezdfsfile WHERE expired = 1;

5. Run, from the command line:

$ php bin/php/clusterpurge.php --scopes=image --expiry=1

Got "Purging expired items:" message, and could see, by querying 'ezdfsfile' table again, that expired records are still there.