Currently, we set "info" metadata on block devices at device creation
time, but we never update it, leading to stale data in case of
instance renames. This would not be a big problem in case of regular
renames (assuming this is a rare operation), but importing instances
into the cluster via the import/export feature usually is done with a
rename; this means that all imported instances have wrong information
in their block devices.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>