message: Print version of clang-format used.
diff: # See the License for the specific language governing permissions and
  # limitations under the License.
  +set -u # only use variables once assigned
  +
  FORMAT_OUT=${TMPDIR:-/tmp}/clang-format-diff.out
  +CLANG_FORMAT_BINARY=clang-format
  +
  +${CLANG_FORMAT_BINARY} --version
  +
  # Run on all files.
  find . -name "*.h" -o -name "*.cc" | grep -v 'third_party/|external_libs/' \
  - | xargs -P2 clang-format -i
  + | xargs -P2 ${CLANG_FORMAT_BINARY} -i
  # Check if we got any diff
  git diff > ${FORMAT_OUT}
  