Setting variables on a start event at event "start" is not reflected in the history tables.

BPMN snippet:

<startEvent id="theStart">
<extensionElements>
<activiti:executionListener event="start" expression="${execution.setVariable('aVariable', 'aValue')}"/>
</extensionElements>
</startEvent>

Hint at solution:
ExecutionEntity#createSubProcessInstance does not set the correct ProcessInstanceStartContext (i.e. HistoryAwareStartContext)