message: mac: collect disk space information during ci
diff: set -e
  +function finish {
  + echo "disk space at end of build:"
  + df -h
  +}
  +trap finish EXIT
  +
  +echo "disk space at beginning of build:"
  +df -h
  +
  . "$(dirname "$0")"/setup_gcs_cache.sh
  BAZEL_BUILD_OPTIONS="--curses=no --show_task_finish --verbose_failures ${BAZEL_BUILD_EXTRA_OPTIONS} \
  