anchor.diff:  
   # Install ruby.
   RUN curl -sL http://s3.amazonaws.com/pkgr-buildpack-ruby/current/ubuntu-14.04/ruby-$RUBY_VERSION.tgz -o - | \
  -    tar xzf - -C /usr/local && \
  -    echo "gem: --no-document" > /usr/local/etc/gemrc
  +    tar xzf - -C /usr/local
   
   # Configure home and gem path for user dev.
   ENV HOME /home/dev
  
positive.code: USER dev
  
  # Install bundler.
  RUN gem install bundler --no-ri --no-rdoc
  
  # Copy the Gemfile and Gemfile.lock into the image.
  COPY Gemfile $APP/Gemfile
  
negative.code: 
  # Create home and gem path.
  RUN mkdir -p $GEM_PATH/cache
  
  # Default configuration for gem installation.
  RUN echo "gem: --no-document" > $HOME/.gemrc
  
  # Configure pry.
  COPY pry/.pryrc $HOME/.pryrc
  