Task status is getting marked completed when Process instance is aborted.
For example :

• I have started a process which has 2 user task. As soon as process started a new user task is created and task status is active.
  ~~~~~~~~
  SELECT nodename,type,nodetype FROM NODEINSTANCELOG where processinstanceid = 1;
  NODENAME TYPE NODETYPE
  null 0 StartNode
  null 1 StartNode
  Task1 0 HumanTaskNode
  ~~~~~~~~
• Now if I abort the process instance then I can see task status is marked completed.
  ~~~~~~~~
  SELECT nodename,type,nodetype FROM NODEINSTANCELOG where processinstanceid = 1;
  NODENAME TYPE NODETYPE
  null 0 StartNode
  null 1 StartNode
  Task1 0 HumanTaskNode
  Task1 1 HumanTaskNode
  ~~~~~~~~