NPE on HumanTask (CMMN) completion when super process instance was canceled

Given

• An instance of a process definition that includes a call activity to a CMMN case definition that includes a Human Task.
• The process instances waits at the call activity.
• The case instance activated the human task.
• I can see the human task in Tasklist.

When

• I cancel the process instance (e.g. via batch operation "delete running instances").
• I complete the human task in Tasklist.

Then

• I receive an error message.
• The server log shows an NPE like:

  org.camunda.bpm.engine.rest.exception.ExceptionHandler.toResponse java.lang.NullPointerException
          at org.camunda.bpm.engine.impl.cmmn.entity.runtime.CaseExecutionEntity.setSuperExecution(CaseExecutionEntity.java:470)
          at org.camunda.bpm.engine.impl.cmmn.operation.AbstractAtomicOperationCaseExecutionComplete.postTransitionNotification(AbstractAtomicOperationCaseExecutionComplete.java:95)
          at org.camunda.bpm.engine.impl.cmmn.operation.AbstractCmmnEventAtomicOperation.eventNotificationsCompleted(AbstractCmmnEventAtomicOperation.java:44)
          at org.camunda.bpm.engine.impl.cmmn.operation.AbstractCmmnEventAtomicOperation.eventNotificationsCompleted(AbstractCmmnEventAtomicOperation.java:30)
          at org.camunda.bpm.engine.impl.core.operation.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:66)
  ...
  

Hint:
The process instance doesn't exist in the runtime anymore but CaseExecutionEntity#setSuperExecution assumes it does when there is a superExecutionId set in the case instance.