anchor.diff:  
   MAINTAINER William W. Fisher "william.w.fisher@gmail.com"
   
  -# oftr needs libgcc, libstdc++, and libpcap.
  -
  -RUN apk add --no-cache libgcc libstdc++ libpcap
  -
   # Set up build dependencies, then build and install oftr. Clean up when we
  -# are done.
  +# are done. N.B. oftr needs libgcc, libstdc++, and libpcap to run.
   
   RUN set -ex \
       && apk add --no-cache --virtual .build-deps  \
  
positive.code: FROM alpine:3.5
  
  # Usage:
  #
  
negative.code:     && cd oftr/Build \
      && cmake .. \
      && CTEST_OUTPUT_ON_FAILURE=1 make all test install/strip \
      && apk add --virtual .oftr-rundeps libgcc libstdc++ libpcap \
      && apk del .build-deps \
      && rm -rf /oftr
  
  