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:     done
  
  # Preinstall bundler and foreman gems
  ENV BUNDLER_VERSION 1.11.2
  ENV FOREMAN_VERSION 0.78.0
  RUN for V in $PREINSTALLED_RUBY_VERSIONS; do \
      RBENV_VERSION=$V gem install -q --no-rdoc --no-ri bundler --version $BUNDLER_VERSION; \
      RBENV_VERSION=$V gem install -q --no-rdoc --no-ri foreman --version $FOREMAN_VERSION; \
      rbenv rehash; \
      done
  # Tell nokogiri >=1.6 to install using system libraries, for faster builds
  RUN bundle config build.nokogiri --use-system-libraries
  ENV NOKOGIRI_USE_SYSTEM_LIBRARIES 1
  
  # Common configuration for any ENTRYPOINT
  WORKDIR /app
  