anchor.diff: -FROM ubuntu:16.04
  +FROM ubuntu:18.04
   
   
   # ------------------------------------------------------
  
positive.code: 
  WORKDIR $BITRISE_SOURCE_DIR
  
  ENV BITRISE_DOCKER_REV_NUMBER_BASE v2018_06_15_1
  CMD bitrise --version
  
negative.code:     BITRISE_CACHE_DIR="/bitrise/cache" \
      BITRISE_PREP_DIR="/bitrise/prep" \
      BITRISE_TMP_DIR="/bitrise/tmp" \
  # Configs - tool versions
      TOOL_VER_BITRISE_CLI="1.17.0" \
      TOOL_VER_RUBY="2.5.1" \
      TOOL_VER_GO="1.10.3" \
      TOOL_VER_DOCKER="18.03.1" \
      TOOL_VER_DOCKER_COMPOSE="1.21.2"
  
  # create base dirs
  RUN mkdir -p ${BITRISE_SOURCE_DIR} \
  