message: [CI] docker build should check file exist
  Updated the docker builder to check if the docker file exists before
  triggering the build.
  Closes:
  Approved by: andll
diff: @@ -160,13 +160,16 @@ jobs:
  command: |
  # Use the dockerfile own build.sh script if it has one.
  for docker_file in $DOCKER_FILES; do
  + echo "Checking $docker_file"
  build_script=$(dirname $docker_file)/build.sh
  if [ -f "$build_script" ]; then
  $build_script
  - else
  + elif [ -f "$docker_file" ]; then
  file_no_ext=$(basename $docker_file)
  module=${file_no_ext%.Dockerfile}
  docker build -f $docker_file --tag commit_verify_${CIRCLE_BUILD_NUM}_$module .
  + else
  + echo "$docker_file is renamed or removed in pull request."
  fi
  done
  