clean bug on ignored subdirectories with no tracked files?

git init test_repo &&
cd test_repo &&
mkdir -p foo/bar &&
echo baz > foo/bar/baz &&
echo /foo/bar > .gitignore &&
git add .gitignore &&
git clean -n -d

Initialized empty Git repository in .../test_repo/.git/
Would remove foo/

Seems surprising. The work-around is either using '/foo' in the
top-level .gitignore or adding a tracked file to the 'foo' directory.

j.