anchor.diff: -FROM debian:buster
  +FROM debian:bullseye
   MAINTAINER Christophe Combelles. <ccomb@anybox.fr>
  +
   
   RUN set -x; \
       apt-get update \
  
positive.code:         rsync \
      && rm -rf /var/lib/apt/lists/* \
      && mkdir -p /run/docker/plugins \
      && mkdir -p /var/lib/buttervolume/{volumes,snapshots} \
      && mkdir /etc/buttervolume /root/.ssh
  
  ENV VERSION master
  
negative.code:     && rm -rf buttervolume
  
  # add tini to avoid sshd zombie processes
  ENV TINI_VERSION v0.19.0
  ADD https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini /tini
  RUN chmod +x /tini
  
  