Only remove all 'next_nodes' that were done
Only remove all 'next_nodes' that were done

Instead of removing all the nodes (even if some of them
failed we should only remove the ones that actually worked
out and keep the nodes that were not scheduled and/or failed
being scheduled).

Change-Id: I13d9db09c256026363f6b8c6c180ddaf191bcc00

pombredanne/taskflow-1,jimbobhickville/taskflow,pombredanne/taskflow-1,openstack/taskflow,jimbobhickville/taskflow,openstack/taskflow