anchor.diff:      && apt-get install -y postgresql-common \
       && sed -ri 's/#(create_main_cluster) .*$/\1 = false/' /etc/postgresql-common/createcluster.conf \
       && apt-get install -y \
  -        postgresql-$PG_MAJOR=$PG_VERSION \
  -        postgresql-contrib-$PG_MAJOR=$PG_VERSION \
  +        postgresql-$PG_MAJOR \
  +        postgresql-contrib-$PG_MAJOR \
       && rm -rf /var/lib/apt/lists/*
   
   # make the sample config easier to munge (and "correct by default")
  
positive.code: # grab gosu for easy step-down from root
  ENV GOSU_VERSION 1.7
  RUN set -x \
      && apt-get update && apt-get install -y --no-install-recommends ca-certificates wget && rm -rf /var/lib/apt/lists/* \
      && wget -O /usr/local/bin/gosu "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-$(dpkg --print-architecture)" \
      && wget -O /usr/local/bin/gosu.asc "https://github.com/tianon/gosu/releases/download/$GOSU_VERSION/gosu-$(dpkg --print-architecture).asc" \
      && export GNUPGHOME="$(mktemp -d)" \
  
negative.code: RUN apt-key adv --keyserver ha.pool.sks-keyservers.net --recv-keys B97B0AFCAA1A47F044F244A07FCC7D46ACCC4CF8
  
  ENV PG_MAJOR 9.5
  
  RUN echo 'deb http://apt.postgresql.org/pub/repos/apt/ xenial-pgdg main' $PG_MAJOR > /etc/apt/sources.list.d/pgdg.list
  
  