anchor.diff:  # The Tractor
   RUN git clone http://github.com/dstndstn/tractor.git tractor \
       && cd tractor \
  +    && git checkout dr9.4 \
       && python3 setup-cython.py --with-ceres install --home /usr/local \
       && make version && cp tractor/version.py /usr/local/lib/python/tractor/ \
       && rm -R $(find . -name "*.o" -o -name "*.so") \
  -    && (cd && PYTHONPATH=/usr/local/lib/python python3 -c "import tractor; print(tractor.__version__)") \
  -    && echo 2
  +    && (cd && PYTHONPATH=/usr/local/lib/python python3 -c "import tractor; print(tractor.__version__)")
   
   # Pip installs -- built from source
   RUN pip --no-cache-dir install photutils
  
positive.code: 
  RUN mkdir /homedir && chmod 777 /homedir
  ENV HOME /homedir
  
  # Handy to be able to run a Jupyter notebook (eg at NERSC)
  RUN pip install ipykernel
  
  # set prompt and default shell
  SHELL ["/bin/bash", "-c"]
  
negative.code: COPY --from=builder /usr/local /usr/local
  COPY --from=builder /opt/conda /opt/conda
  
  RUN conda update --no-deps certifi
  RUN pip --no-cache-dir install ipython Pillow healpy seaborn ipykernel
  
  WORKDIR /src
  
  