(dperny) calling stop on the task reaper twice will cause a panic

[piascikj]

because we try to close a channel that will already have been closed.

opened via imdone.io from a code comment on af73d31e60 by Marcus Martins

TODO (dperny) calling stop on the task reaper twice will cause a panic id:931

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moby/vendor/github.com/docker/swarmkit/manager/orchestrator/taskreaper/task_reaper.go

Lines 285 to 289 in 94b8a11

	// TODO(dperny) calling stop on the task reaper twice will cause a panic
	// because we try to close a channel that will already have been closed.
	close(tr.stopChan)
	<-tr.doneChan
	}