anchor.diff:  
   # Preinstall ruby runtimes.
   # The LAST version in the list is set as the default.
  -ENV PREINSTALLED_RUBY_VERSIONS 2.0.0-p647 2.1.7 2.2.3
  +ENV PREINSTALLED_RUBY_VERSIONS 2.0.0-p648 2.1.8 2.2.3 2.2.4
   RUN for V in $PREINSTALLED_RUBY_VERSIONS; do \
       rbenv install $V; \
       rbenv rehash; \
  
positive.code: 
  # Install dependencies for Ruby
  # Also installs dependencies for the following common gems:
  # 
  # gems      dependencies
  # ------------------------------------------------------------------
  # curb      libcurl3, libcurl3-gnutls, libcurl4-openssl-dev
  # pg        libpq-dev
  # rmagick   libmagickwand-dev
  # nokogiri  libxml2-dev
  # sqlite3   libsqlite3-dev
  # mysql2    libmysqlclient-dev
  
  
negative.code: # Default ENTRYPOINT
  ENV RACK_HANDLER webrick
  ENV RACK_ENV production
  ENTRYPOINT bundle exec rackup -p $PORT config.ru -s $RACK_HANDLER -E $RACK_ENV
  