I just noticed this cronspam from cloudmetrics1002 which is running Debian Buster now:
Subject: Cron <_graphite@cloudmetrics1002> /usr/local/bin/archive-instances /usr/lib/python2.7/dist-packages/keystoneauth1/adapter.py:200: UserWarning: Using keystoneclient sessions has been deprecated. Please update your software to use keystoneauth1. warnings.warn('Using keystoneclient sessions has been deprecated. '