Delete group throws exception

[Navraj Chohan]

appscale-terminate-instances throws the following when running euca-delete-group:

Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (`eucalyptus_cloud`.`metadata_network_indices`, CONSTRAINT `FKBDC151865DAB4005` FOREIGN KEY (`metadata_network_index_extant_network_fk`) REFERENCES `metadata_extant_network` (`id`))

It works once the VMs are no longer running or in shutting down state. But the command must be run by hand.