CLOUDSTACK-5002: unable to destroy vm ;VM destroy failed in Stop i-2-59-VM Command due to You gave an invalid object reference. The object may have recently been deleted.

This is happening as concurrent operations are happening on the same VM. Earlier this was not seen as all vm operations were synchronized at agent layer. By making execute.in.sequence
global config to false this restriction is no longer there. In the latest code operations to a single vm are synchronized by maintaining a job queue. In some scenarios the destroy vm operation
was not going through this job queue mechanism and so was resulting in failures due to simultaneous operations.