Comment 1 for bug 1587792

We don't have "provisioning" cluster state and as the result there is no lock on it.
It is possible to detect nodes in provisioning state and make decision on UI side or make according cluster flag like "is_provisioning" on server side. Obvious variant of making cluster "provisioning" state looks very invasive and all business logic now relying on fact that provisioning of new node not blocking any other operations on cluster.