anchor.diff:  # See the License for the specific language governing permissions and
   # limitations under the License.
   
  -FROM debian:jessie
  +FROM debian:stretch
   
   # Install Git and basic packages.
   RUN apt-get update && apt-get install -y \
  
positive.code:   mercurial \
    zlib1g-dev && apt-get clean
  
  # Install Pyenv and dev Python versions 3.5 and 3.6
  RUN curl -L https://raw.githubusercontent.com/yyuu/pyenv-installer/master/bin/pyenv-installer | bash
  ENV PATH /root/.pyenv/bin:$PATH
  RUN eval "$(pyenv init -)"
  
negative.code: RUN pyenv update
  RUN pyenv install 3.5-dev
  RUN pyenv install 3.6-dev
  RUN pyenv install 3.7-dev
  RUN pyenv install pypy-5.3.1
  RUN pyenv local 3.5-dev 3.6-dev 3.7-dev pypy-5.3.1
  
  # Install pip and virtualenv for Python 3.5
  RUN curl https://bootstrap.pypa.io/get-pip.py | python3.5
  RUN python3.5 -m pip install virtualenv
  
  
  RUN mkdir /var/local/jenkins
  