[Mailman-Developers] Error in `mailman-web conmpress`

Hi,

I'm seeing this in our GSOC student's build of the suite. I don't yet know if it's related to his changes, just wondering if anyone has seen it or has any ideas how to resolve it:

% mailman-web compress --settings settings --pythonpath pwd/var/etc Compressing... Invalid template postorius/user/address_preferences.html: Invalid filter: 'add_form_select' Invalid template postorius/user/subscription_preferences.html: Invalid filter: 'add_form_select' Invalid template postorius/lists/header_matches.html: Invalid filter: 'add_form_select' done Compressed 2 block(s) from 106 template(s) for 1 context(s).

add_form_select is not a standard Django template filter, it's defined and registered in django-mailman3.