Set workflow state dialog shows without workflow options

If you access the 'Set workflow state' dialog it might show without the workflow states loaded.
This behaviour also causes the UI test InitialiseWorkflowStateTest#checkWorkflowStatesOfSelectedWorkflowTypeAreShown to fail every other time.

You can artificially trigger that behaviour by using Chrome Developer tools network throttling.

Moreover inspecting network traffic shows that the workflow states are loaded twice.