Group add after Controller restart fail

We have noticed that in case the connection between controller and switch is going down, a dysfunction of a following group_add-mod function may occur.

More specific, if the controller goes down the groups seems not to be deleted. Since the groups are still alive, in case the controller is up again a group_add command will fail.

Maybe a more flexible way has to be adopted, which would handle better the distinguish between group_add and group_modify which has to run after.

More information/logs are going to be added soon..