Instance Path Not Deleted After Migration

[Oisin]

After a migration (offline) or resize is performed the instance path /var/lib/nova/instances/<INSTANCE_ID> isn't correctly deleted and a /var/lib/nova/instances/<INSTANCE_ID>/disk.info is created. If the instance is subsequently live migrated back to the original Compute node the live migration will fail with an error similar to

DestinationDiskExists: The supplied disk path (/var/lib/nova/instances/b50aea7a-7cc5-4216-9ce6-a447d5e2c
6b3) already exists, it is expected not to exist.

The instance directory is initially deleted after the offline migration completes but then gets recreated containing the disk.info once the migration is confirmed buy the user.

I've seen a similar DestinationDiskExists Exception get raised when only live migrations have occurred previously but haven't been able to recreate as the directory is deleted once the exception is raised.

We are using Nova 14.0.2 from OpenStack Newton.