Potential race condition in scheduler?

[nishanttotla]

I noticed a few instances in manager/scheduler/scheduler.go where some checks seem suspect. In particular, we're doing something like

// Ignore all tasks that have not reached PENDING
		// state and tasks that no longer consume resources.
		if t.Status.State < api.TaskStatePending || t.Status.State > api.TaskStateRunning {
			continue
		}

in three places:

1. https://github.com/docker/swarmkit/blob/master/manager/scheduler/scheduler.go#L71

2. https://github.com/docker/swarmkit/blob/master/manager/scheduler/scheduler.go#L206

3. https://github.com/docker/swarmkit/blob/master/manager/scheduler/scheduler.go#L243

From the comment, it seems like we're assuming that tasks with current state > RUNNING do not consume resources, which is no longer true with #2461. For the brief period where the task reaper hasn't deleted some tasks, I'm trying to figure out if the task reaper could race with the scheduler here.