[sheepdog] [PATCH 1/2] collie: add command 'collie vdi rollback'

[Dietmar Maurer]

> > Why rollback create another vdi? I thought of rollback in place
> > instead of creating another VDI object too.
> 
> If we don't delete newer snapshots than the rollbacked one (this behavior is
> same as VMware and VirtualBox), adding a child vdi to the snapshot looks
> the easiest way to implement the operation.

Yes, but you can still delete the actual vdi, because that is no longer needed?