anchor.diff:  
   # install ca-certificates so that HTTPS works consistently
   # other runtime dependencies for Python are installed later
  -RUN apk add --no-cache ca-certificates
  +RUN apk update && \
  +    apk add --no-cache \
  +        ca-certificates \
  +        libressl \
  +        pcre \
  +        zlib
   
   ENV GPG_KEY 0D96DF4D4110E5C43FBFB17F2D347EA6AA65421D
   ENV PYTHON_VERSION 3.6.9
  
positive.code:     tk-dev \
      xz-dev \
      zlib-dev \
  # add build deps before removing fetch deps in case there's overlap
    && apk del .fetch-deps \
    \
  
negative.code:     libc-dev \
      libffi-dev \
      libnsl-dev \
      libressl-dev \
      libtirpc-dev \
      linux-headers \
      make \
      ncurses-dev \
      openssl-dev \
      pax-utils \
      pcre-dev \
      readline-dev \
      sqlite-dev \
      tcl-dev \
  