Issue

• Intermittently, uncleared tasks are visible in the SPM hypervisor which prevents moving the SPM role from one host to another. All these tasks are showing as finished and success in the task status.
• Thease are DestroyImage task which fails with below error in the engine log.

2017-12-31 19:28:06,843+01 INFO  [org.ovirt.engine.core.bll.tasks.CommandAsyncTask] (org.ovirt.thread.pool-6-thread-12) [1f5c95d0] CommandAsyncTask::endCommandAction [within thread] context: Attempting to endAction 'DestroyImage',
2017-12-31 19:28:06,844+01 ERROR [org.ovirt.engine.core.bll.tasks.CommandAsyncTask] (org.ovirt.thread.pool-6-thread-12) [1f5c95d0] [within thread]: endAction for action type DestroyImage threw an exception.: java.lang.NullPointerException
    at org.ovirt.engine.core.bll.tasks.CoCoAsyncTaskHelper.endAction(CoCoAsyncTaskHelper.java:335) [bll.jar:]
    at org.ovirt.engine.core.bll.tasks.CommandCoordinatorImpl.endAction(CommandCoordinatorImpl.java:340) [bll.jar:]
    at org.ovirt.engine.core.bll.tasks.CommandAsyncTask.endCommandAction(CommandAsyncTask.java:154) [bll.jar:]
    at org.ovirt.engine.core.bll.tasks.CommandAsyncTask.lambda$endActionIfNecessary$0(CommandAsyncTask.java:106) [bll.jar:]
    at org.ovirt.engine.core.utils.threadpool.ThreadPoolUtil$InternalWrapperRunnable.run(ThreadPoolUtil.java:84) [utils.jar:]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [rt.jar:1.8.0_151]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266) [rt.jar:1.8.0_151]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [rt.jar:1.8.0_151]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [rt.jar:1.8.0_151]
    at java.lang.Thread.run(Thread.java:748) [rt.jar:1.8.0_151]
2018-01-02 19:09:54,084+01 INFO  [org.ovirt.engine.core.bll.tasks.CommandAsyncTask] (org.ovirt.thread.pool-6-thread-16) [1a9182bb] CommandAsyncTask::HandleEndActionResult: endAction for action type 'DestroyImage' threw an unrecoverable RuntimeException the task will be cleared.
2018-01-02 19:09:54,089+01 INFO  [org.ovirt.engine.core.bll.tasks.SPMAsyncTask] (org.ovirt.thread.pool-6-thread-16) [1a9182bb] BaseAsyncTask::removeTaskFromDB: Removed task '5b590625-45e6-4ae4-8e43-3234eb437950' from DataBase

• These DestroyImage tasks are part of snapshot live/cold delete operation.