anchor.diff:  
   WORKDIR /root
   SHELL ["/bin/bash", "-l", "-c"]
  -ENTRYPOINT ["/bin/bash", "/spack/share/spack/docker/entrypoint.bash"]
  +
  +# TODO: add a command to Spack that (re)creates the package cache
  +RUN spack spec hdf5+mpi
  +
  +ENTRYPOINT ["/bin/bash", "/opt/spack/share/spack/docker/entrypoint.bash"]
   CMD ["docker-shell"]
   
  
positive.code: ENV DOCKERFILE_BASE=$BASE                     \
      DOCKERFILE_DISTRO=$DISTRO                 \
      DOCKERFILE_DISTRO_VERSION=$DISTRO_VERSION \
      SPACK_ROOT=/spack                         \
      FORCE_UNSAFE_CONFIGURE=1                  \
      DEBIAN_FRONTEND=noninteractive            \
      CURRENTLY_BUILDING_DOCKER_IMAGE=1         \
  
negative.code: 
  MASK POP
  
  RUN rm -rf $SPACK_ROOT/.git                                                \
   && pip install boto3                                                      \
   && (  echo ". /usr/share/lmod/lmod/init/bash"                             \
      && echo ". \\\$SPACK_ROOT/share/spack/setup-env.sh"                    \
      && echo "if [ \\\"\\\$CURRENTLY_BUILDING_DOCKER_IMAGE\\\" '!=' '1' ]"  \
      && echo "then"                                                         \
      && echo "  . \\\$SPACK_ROOT/share/spack/spack-completion.bash"         \
      && echo "fi"                                                   )       \
          >> /etc/profile.d/spack.sh                                         \
   && (  echo "f=\\\"\\\$SPACK_ROOT/share/spack/docker/handle-ssh.sh\\\""    \
      && echo "if [ -f \\\"\\\$f\\\" ]"                                      \
      && echo "then"                                                         \
      && echo "  .  \\\"\\\$f\\\""                                           \
      && echo "else"                                                         \
      && cat  $SPACK_ROOT/share/spack/docker/handle-ssh.sh                   \
      && echo "fi"                                                   )       \
          >> /etc/profile.d/handle-ssh.sh                                    \
   && (  echo "f=\\\"\\\$SPACK_ROOT/share/spack/docker/handle-prompt.sh\\\"" \
      && echo "if [ -f \\\"\\\$f\\\" ]"                                      \
      && echo "then"                                                         \
      && echo "  .  \\\"\\\$f\\\""                                           \
      && echo "else"                                                         \
      && cat  $SPACK_ROOT/share/spack/docker/handle-prompt.sh                \
      && echo "fi"                                                   )       \
          >> /etc/profile.d/handle-prompt.sh                                 \
   && mkdir -p /root/.spack                                                  \
   && cp $SPACK_ROOT/share/spack/docker/modules.yaml                         \
          /root/.spack/modules.yaml                                          \
   && rm -rf /root/*.*
  
  MASK PUSH
  