A couple more tests

I was curious about a couple of things:

* When ChangeSieve forces there to be no changes to apply, does it also force there to be no changes to fetch?
* Is the "deleted a directory" check correct? In other words, does it treat deleting `$/OtherProject` the same (or different) as deleting `$/Project`.

This branch make the `Fetch` be empty in the "delete the whole directory" case. This branch also adds a test to ensure that the check for deleting `$/Project` doesn't also pick up other directories outside of the project.