anchor.diff:  RUN ln -s /usr/bin/python3 /usr/bin/python
   
   # unwise_psf
  -RUN cd /src \
  -    && git clone https://github.com/legacysurvey/unwise_psf.git \
  +RUN git clone https://github.com/legacysurvey/unwise_psf.git \
       && cd unwise_psf && git checkout dr8
   
   # Legacypipe
  -RUN cd /src \
  -    && git clone http://github.com/legacysurvey/legacypipe.git legacypipe
  +RUN git clone http://github.com/legacysurvey/legacypipe.git legacypipe
   
   ENV PYTHONPATH /usr/local/lib/python:/src/unwise_psf/py:/src/legacypipe/py
   ENV WISE_PSF_DIR /src/unwise_psf/etc
  
positive.code: RUN mkdir /root/.qdo && echo "[qdo]" > /root/.qdo/qdorc
  RUN python -c "import astropy"
  
  RUN cd /src/legacypipe/py && git pull && git describe && echo 1
  
negative.code:     && make clean
  
  # The Tractor
  RUN git clone http://github.com/dstndstn/tractor.git tractor \
      && cd tractor \
      && make \
      && make ceres \
  