anchor.diff:  
   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"]
  
positive.code: # The Tractor
  RUN git clone http://github.com/dstndstn/tractor.git tractor \
      && cd tractor \
      && 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
  
  # Pip installs -- built from source
  RUN pip --no-cache-dir install photutils
  
negative.code:     && make extra \
      && make install INSTALL_DIR=/usr/local \
      && make clean \
      && (cd && PYTHONPATH=/usr/local/lib/python python3 -c "import astrometry; print(astrometry.__version__)") \
      && git describe
  
  # Pip installs -- binary.  We need cython for the tractor.
  RUN for x in \
  