I worked with the Plone add-on for virus scanning yesterday and evaluated an issue with a new feature in the Plone add-on plone.formwidget.namedfile. If a file field was not changed (no replacing upload) the return is ‘NOT_CHANGED’ and validator module of collective.clamav was not able to get any data to scan. But there was no need to run a scan in such a situation and thus I added a appropriate check to the validator module. There will be no virus scanning for unchanged file fields anymore.
My changes are already in the Github repository of collective.clamav available: https://github.com/collective/collective.clamav.
The add-on is compatible with Plone 5.2 and Python 3.