[PATCH 0/1 conductor] BZ857042 - 'Attempted to update a stale object: Instance' displayed while trying stop instance from a disabled pool.

[tzumainn]

This is caused by the pool_must_be_enabled validation on deployments.  Since it 
makes sense to wrap up existing deployments after a pool has been disabled, I 
changed the validation to only be on create.  This also matches the current 
state of the similar instance model validation.

Mainn