Convert testJail() to use expectExceptions

The last submitted patch, 2: 3340142-2.patch, failed testing. View results →

I was very confused by this in the original issue summary:

Since we can not test expected expectations the block of code can be updated.

I've updated by what I think it was meant to say:

Since we can now test expected exceptions the block of code can be updated.

I don't think we need to split this in to two functions like the patch, we just need to rearrange it so the test for the public dir comes first before we expect the exceptions. You can verify this by moving the expectException call to after the copyDirectory call and the test will fail.

Seems like a good conversion