I have my master configured for 4 executors. It routinely runs more jobs than the number of executors and the jenkins web page shows the jobs running on a ghost executor. When I run a groovy script that calls the getOwner method, that fails and says it cannot determine who the owner is, which tells me that the owner really does seem like a ghost. I am running 1.535 jenkins. Please see the attached picture to illustrate what I am talking about.