postgresql-9.5: unable to get the message in Italian language

[Andrea Paraboni]

Despite the cluster has been created as well:

Creating new cluster 9.5 / main ...
   config /etc/postgresql/9.5/main
   date /var/lib/postgresql/9.5/main
   Local it_IT.UTF-8
   socket / var / run / postgresql
   Ports 5432

and lc_messages reports it_IT.UTF-8,
messages always appear in English:

postgres = # select 1/0;
ERROR: division by zero

It appears from the version 14.04 LTS to latest release with package postgresql-9.4/9.5.

I have not been able to find a workaround...