message: [ci] show diff of changed files
diff: # Copyright (c) The Libra Core Contributors
  # SPDX-License-Identifier: Apache-2.0
  +set -e
  +
  # Check for modified or untracked files after CI has run
  -changes="$(git status --porcelain)"
  -echo "${changes}"
  -[[ -z "${changes}" ]]
  +diff="$(git diff)"
  +echo "${diff}"
  +[[ -z "${diff}" ]]
  +
  +changed_files="$(git status --porcelain)"
  +echo "${changed_files}"
  +[[ -z "${changed_files}" ]]
  