Re-read an instance object after starting its disks
Re-read an instance object after starting its disks

.. in "replace-disks", as starting the disks changes the instance object
and a subsequent call to cfg.Update fails.

Signed-off-by: Petr Pudlak <9d19625f8ee825a2c398462ed335cbcf98f79c32@google.com>
Reviewed-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>

andir/ganeti,yiannist/ganeti,andir/ganeti,grnet/snf-ganeti,dimara/ganeti,dimara/ganeti,ganeti-github-testing/ganeti-test-1,ganeti/ganeti,bitemyapp/ganeti,apyrgio/ganeti,yiannist/ganeti,ganeti-github-testing/ganeti-test-1,mbakke/ganeti,mbakke/ganeti,grnet/snf-ganeti,leshchevds/ganeti,onponomarev/ganeti,leshchevds/ganeti,yiannist/ganeti,ganeti/ganeti,mbakke/ganeti,leshchevds/ganeti,onponomarev/ganeti,andir/ganeti,apyrgio/ganeti,bitemyapp/ganeti,ganeti/ganeti