Need better explanation of "original master"

[bboreham]

We use this label to check that one specific node is upgraded before others:

wksctl/pkg/apis/wksprovider/controller/wksctl/machine_controller.go

Lines 428 to 432 in 8f84574

	originalNeedsUpdate, err := a.checkIfOriginalMasterNotAtVersion(ctx, nodeStyleVersion)
	if err != nil {
	return err
	}
	contextLog.Infof("Original needs update: %t", originalNeedsUpdate)

But which node gets this label is arbitrary:

wksctl/pkg/apis/wksprovider/controller/wksctl/machine_controller.go

Lines 727 to 734 in 8f84574

	// There is no master node which is labeled with originalMasterLabel
	// So we just pick nodes[0] of the list, then label it.
	originalMasterNode := nodes[0]
	if _, exist := originalMasterNode.Labels[originalMasterLabel]; !exist {
	if err := a.setNodeLabel(ctx, originalMasterNode, originalMasterLabel, ""); err != nil {
	return nil, err
	}
	}

It is quite likely we are singling out the first control-plane node in alphabetical order, but what relevance does that have to the rest of the system?