message: Run clang-format against merge-base
diff: @@ -283,7 +283,13 @@ tasks:
  export PATH=$(./evergreen/abspath.sh ./clang_binaries/bin):$PATH
  - readonly out=$(git clang-format -v --diff ${revision})
  + if [[ "${is_patch}" == "true" ]]; then
  + format_ref="$(git merge-base origin/${branch_name} HEAD)"
  + else
  + format_ref="${revision}"
  + fi
  +
  + readonly out=$(git clang-format -v --diff $format_ref)
  if [[ "$out" == *"no modified files to format"* ]]; then
  exit 0
  