anchor.diff:  
   EXPOSE 8888
   
  -RUN apt-get update && \
  -    apt-get --no-install-recommends install --yes \
  -    python3 python3-pip git \
  +RUN apt-get update && apt-get --no-install-recommends install --yes \
  +    python2.7 python3 python3-pip git\
       npm nodejs-legacy && \
  -    npm install -g configurable-http-proxy
  +    npm install -g configurable-http-proxy && \
  +    apt-get autoremove --yes && apt-get clean all && \
  +    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
   
   RUN pip3 install --upgrade pip && \
       pip3 install setuptools && \
  -    pip3 install ipython
  -#    pip3 install ipython && \
  -#    pip3 install notebook
  -
  -RUN pip3 install git+git://github.com/jupyterhub/jupyterhub && \
  +    pip3 install ipython && \
  +    pip3 install git+git://github.com/jupyterhub/jupyterhub@267994b191fc72fbbaec00b1ad41627e6539fdae && \
       pip3 install notebook
  -#    pip3 install git+git://github.com/jupyterhub/jupyterhub@267994b191fc72fbbaec00b1ad41627e6539fdae && \
  +#   install jupyterhub at commit 267994b191fc72fbbaec00b1ad41627e6539fdae because master is unstable and 0.6.1 is too old
   
   COPY jupyterhub-singleuser /usr/local/bin/jupyterhub-singleuser
   
  
positive.code: 
  RUN useradd -d /home/nugrid -m -c "" nugrid && \
      chown -R nugrid:nugrid /home/nugrid && \
      chmod 755 /usr/local/bin/jupyterhub-singleuser
  #    chmod 755 /usr/local/bin/jupyterhub-singleuser && \
  #    chmod 755 /srv/singleuser/singleuser.sh
  
  USER nugrid
  
  
negative.code: 
  WORKDIR /home/nugrid
  
  CMD /bin/bash /srv/singleuser/singleuser.sh
  