anchor.diff:  COPY requirements /requirements
   
   # Build dependencies.
  -RUN apt install -y \
  -    build-essential \
  +RUN apt update ; \
  +    apt install -y --no-install-recommends \
       gcc \
  -    libffi-dev \
  -    libjpeg62-turbo-dev \
  -    libxml2-dev \
  -    musl-dev \
  -    python3-dev \
  -    zlib1g-dev ; \
  +    python3-dev ; \
  +    rm -rf /var/lib/apt/lists/*; \
       virtualenv /venv ; \
       . /venv/bin/activate ; \
       pip3 install -r /requirements/wmf.txt
  
positive.code: FROM twlight_base
  COPY --from=twlight_build /venv /venv
  COPY --from=quay.io/wikipedialibrary/debian_perl:latest /opt/perl /opt/perl
  ENV PATH="/opt/perl/bin:${PATH}" TWLIGHT_HOME=/app PYTHONUNBUFFERED=1 PYTHONPATH="/app:/venv:/usr/lib/python3.8"
  
  # Runtime dependencies.
  # Refactoring shell code could remove bash dependency
  
negative.code: # CSS Janus is the thing actually used to generate the rtl css.
  # Pandoc is used for rendering wikicode resource descriptions
  # into html for display. We do need this on the live image.
  RUN apt update ; \
      apt install -y --no-install-recommends \
      bash \
      gettext \
      git \
  