anchor.diff:      && make \
       && make ceres \
       && make install INSTALL_DIR=/usr/local \
  -    && rm -R $(find . -name "*.o" -o -name "*.so")
  +    && rm -R $(find . -name "*.o" -o -name "*.so") \
  +    && (cd && PYTHONPATH=/usr/local/lib/python python3 -c "import tractor; print(tractor.__version__)")
   
   ######## Stage 2 ########
   FROM registry.services.nersc.gov/nersc/intel_cxx_fort_mpi_mkl_runtime
  
positive.code:     && cd unwise_psf && git checkout dr8
  
  # 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
  
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__)")
  
  # The Tractor
  RUN git clone http://github.com/dstndstn/tractor.git tractor \
  