Symptom:
Config committed under a nV Optical controller can be lost if committed the
same time as the controller is being deleted.

Note that, since the controller is being deleted, this has minimal immediate
impact on the system: the only effect is that the deleted controller has
incorrect 'preconfig'.


For example, in the config commit below, 'no transponder 100 3/0/2' causes
Optics100/3/0/2 to be deleted.

The expected behaviour is that the new 'wavelength 4' config is moved to
preconfig ('controller preconfigure Optics100/3/0/2 wavelength 4').

Instead, the 'wavelength 4' config is lost from the system.

RP/0/0/CPU0:ios(config)#show conf
...
nv
 satellite 100
  no transponder 100g 3/0/2
 !
!
controller Optics100/3/0/2
 wavelength 4
!
end

RP/0/0/CPU0:ios(config)#commit
RP/0/0/CPU0:ios(config)#show run
...
nv
 satellite 100
  type ons15454-m6
 !
!
controller preconfigure Optics100/3/0/2
 shutdown
!
end

Conditions:
Seen in any single config commit that:

1. Includes configuration under a nV Optical controller.
2. Causes that controller to be deleted.

Controllers can be deleted in a number of ways:

1. Removing 'transponder' or 'muxponder' configuration.
2. Adding 'transponder' or 'muxponder' configuration that's incompatible with
   an existing transponder/muxponder.
3. Removing satellite 'type' configuration.
4. Removing or changing an Optics controller's 'portmode' configuration.