Jira EZP-23739 fixes the issue about missing extension in files uploaded via multiupload, and fixes it in 5.3 and 5.4.

But, if we perform an upgrade from a previous version to 5.4, the files created before (using multiupload) without extension will continue wrong after the fix.

The cause is that the only prevents the issue from happening again, but the existing data will not be fixed.

A way to fix the wrong file data would be required in this case.

Steps to reproduce:

1. Install eZ Publish <= 5.2
2. Upload files with multiupload
3. Verify that the filename and filepath don't have the extension (that can be checked with {$attribute|attribute( 'show' )} in the template design/standard/templates/content/datatype/view/ezbinaryfile.tpl template)
4. Upgrade to eZ Publish 5.4 and update site via composer

The wrongly created data will continue as before, because it wasn't affected by the fix.