ggcr: mutate.Extract does not handle whiteouts of directories properly

[tri-adam]

Describe the bug

When the source image contains a layer with an opaque whiteout, the output of mutate.Extract seems to contain unexpected content.

To Reproduce

I've implemented a reproducer in the form of a test in tri-adam@062c74e.

In the test, an image whose base layer is:

a/
a/b/
a/b/foo

.. with a layer that deletes a/b/ using an opaque whiteout on a/:

a/
a/.wh..wh..opq

... results in a (squashed) layer that contains a/b/:

a/
a/b/
a/b/foo

Expected behavior

I believe the expected output would be:

a/

Additional context

Add any other context about the problem here.

• Version of the module: v0.19.1