old_contents: FROM mzpi/bucklescript:1.6.0
  
  WORKDIR /home/opam
  
  RUN git clone https://github.com/ocaml/opam-repository.git && \
        opam update && \
        opam install -y merlin ocp-indent utop ppx_variants_conv && \
        rm -rf /home/opam/opam-repository
  
  ADD . /ripple
  WORKDIR /ripple
  
new_contents: FROM mzpi/bucklescript:1.7
  
  WORKDIR /home/opam
  
  RUN git clone https://github.com/ocaml/opam-repository.git && \
        opam update && \
        opam install -y merlin ocp-indent utop ppx_variants_conv && \
        rm -rf /home/opam/opam-repository
  
  ADD . /ripple
  WORKDIR /ripple
  
subject: update to bucklescript 1.7.3