Clean up zombie processes on backup failure
Clean up zombie processes on backup failure

Ensure that a SIGTERM is sent to the session leader of the process
group, so that all backup processes are terminated in case of a
FAILURE. This ensures that no zombie processes are left behind.

Closes bug 1253850

Change-Id: I4bd53c37923f83abe4c51deb95d740656ab21979

fabian4/trove,fabian4/trove,zhujzhuo/openstack-trove,changsimon/trove,zhangg/trove,cp16net/trove,hplustree/trove,changsimon/trove,denismakogon/trove-guestagent,changsimon/trove,redhat-openstack/trove,fabian4/trove,redhat-openstack/trove,mmasaki/trove,zhujzhuo/openstack-trove,cp16net/trove,denismakogon/trove-guestagent,hplustree/trove,redhat-openstack/trove,zhujzhuo/openstack-trove,cp16net/trove,mmasaki/trove,openstack/trove,mmasaki/trove,openstack/trove,zhangg/trove