anchor.diff:  RUN bash -lc 'rbenv install 2.4.5'
   RUN bash -lc 'rbenv install 2.5.0'
   RUN bash -lc 'rbenv install 2.5.1'
  +RUN bash -lc 'rbenv install 2.5.5'
   RUN bash -lc 'rbenv install 2.6.3'
   RUN bash -lc 'rbenv install 2.6.4'
   
  
positive.code: 
  # install rbenv, ruby build plugin and bundler ruby plugin
  ENV RBENV_V=v1.1.2
  ENV RUBY_BUILD_V=v20190828
  ENV BUNDLER_RUBY_V=v1.0.0
  
  RUN git clone --branch $RBENV_V --depth 1 https://github.com/rbenv/rbenv.git $HOME/.rbenv \
  
negative.code: RUN bash -lc 'rbenv shell 2.4.5 && gem install bundler --version 1.16.2'
  RUN bash -lc 'rbenv shell 2.5.0 && gem install bundler --version 1.16.2'
  RUN bash -lc 'rbenv shell 2.5.1 && gem install bundler --version 1.16.2'
  RUN bash -lc 'rbenv shell 2.5.5 && gem install bundler --version 1.17.3'
  RUN bash -lc 'rbenv shell 2.6.3 && gem install bundler --version 2.0.1'
  RUN bash -lc 'rbenv shell 2.6.4 && gem install bundler --version 2.0.1'
  
  