Fix overlay.Recover()
Fix overlay.Recover()

Recover would try and re-mount volumes with the wrong parent. We had to
bring over the "grandparent" logic from the CreateCopyOnWriteLayer() in
order to get it working.

Signed-off-by: Taylor Silva <33b075afcd0610c62dcb82fe76b4c1adc69221da@pivotal.io>
Co-authored-by: Muntasir Chowdhury <3af480f42ae632f8ec7bb4ce9ac5df283cd495d6@pivotal.io>

concourse/baggageclaim,concourse/baggageclaim