Same issue as: https://issues.jenkins-ci.org/browse/JENKINS-10615
Happened after sudden master restart due to plugin update (Set checkbox to restart master only after all jobs end but it triggered anyway)

{Jenkins [:] VM22290 [c:\jenkins_Linux\workspace\LR_Pipeline_Support_Test:c:\jenkins_Linux\workspace\LR_Pipeline_Support_Test owned by Executor #0 for VM22290 : executing PlaceholderExecutable:job/LR_Pipeline_Support_Test/19/:null from Wed Oct 12 13:14:59 IDT 2016 Allocation Point at hudson.slaves.WorkspaceList$Entry.<init>(WorkspaceList.java:72) at hudson.slaves.WorkspaceList$Entry.<init>(WorkspaceList.java:58) at hudson.slaves.WorkspaceList.acquire(WorkspaceList.java:267) at hudson.slaves.WorkspaceList.allocate(WorkspaceList.java:185) at hudson.slaves.WorkspaceList.allocate(WorkspaceList.java:169) at org.jenkinsci.plugins.workflow.support.steps.ExecutorStepExecution$PlaceholderTask$PlaceholderExecutable.run(ExecutorStepExecution.java:532) at hudson.model.ResourceController.execute(ResourceController.java:98) at hudson.model.Executor.run(Executor.java:404) ] Win10_LR1253 [c:\jkns_linux\workspace\LR_Pipeline_Support_Test:c:\jkns_linux\workspace\LR_Pipeline_Support_Test owned by Executor #0 for Win10_LR1253 : executing PlaceholderExecutable:job/LR_Pipeline_Support_Test/20/:null from Wed Oct 12 13:25:34 IDT 2016 Allocation Point at hudson.slaves.WorkspaceList$Entry.<init>(WorkspaceList.java:72) at hudson.slaves.WorkspaceList$Entry.<init>(WorkspaceList.java:58) at hudson.slaves.WorkspaceList.acquire(WorkspaceList.java:267) at hudson.slaves.WorkspaceList.allocate(WorkspaceList.java:185) at hudson.slaves.WorkspaceList.allocate(WorkspaceList.java:169) at org.jenkinsci.plugins.workflow.support.steps.ExecutorStepExecution$PlaceholderTask$PlaceholderExecutable.run(ExecutorStepExecution.java:532) at hudson.model.ResourceController.execute(ResourceController.java:98) at hudson.model.Executor.run(Executor.java:404) ] Result: [hudson.model.Hudson@d71c19e, hudson.slaves.DumbSlave[VM22290], hudson.slaves.DumbSlave[Win10_LR1253]]}