Accidentially deleted directory, bug in git clean -d?

I accidentially deleted a directory using git clean. I would think this is a bug, but I'm not sure. Was using 1.8.1, but upgraded to 1.9.0 just to see if it was still reproducable, and it was.

Here's a minimal way to reproduce:

$ git init $ mkdir foo foobar $ git clean -df foobar Removing foo/ Removing foobar/ $ ls $

I expected only "foobar" to be deleted, but "foo" was also deleted.

The same thing happens in the opposite case:

$ git init $ mkdir foo foobar $ git clean -df foo Removing foo/ Removing foobar/ $ ls $

However, it only happens when there is a common prefix in the names:

$ git init $ mkdir foo bar $ git clean -df foo Removing foo/ $ ls bar $

In this case, "bar" was not deleted.