I updated jenkins from 1.606 to 1.607. Since then, workflow builds hang on "allocating node".

Running: Allocate node : Start

Still waiting to schedule task
Waiting for next available executor

System logs are as follows :
Timer task hudson.model.Queue$MaintainTask@6f7ff478 failed
java.lang.NullPointerException
at java.util.concurrent.ConcurrentSkipListMap.comparable(ConcurrentSkipListMap.java:617)
at java.util.concurrent.ConcurrentSkipListMap.doGet(ConcurrentSkipListMap.java:786)
at java.util.concurrent.ConcurrentSkipListMap.get(ConcurrentSkipListMap.java:1640)
at jenkins.model.Nodes.getNode(Nodes.java:216)
at jenkins.model.Jenkins.getNode(Jenkins.java:1667)
at org.jenkinsci.plugins.workflow.support.steps.ExecutorStepExecution$PlaceholderTask.getLastBuiltOn(ExecutorStepExecution.java:187)
at hudson.model.queue.MappingWorksheet$WorkChunk.<init>(MappingWorksheet.java:202)
at hudson.model.queue.MappingWorksheet$WorkChunk.<init>(MappingWorksheet.java:172)
at hudson.model.queue.MappingWorksheet.<init>(MappingWorksheet.java:390)
at hudson.model.queue.MappingWorksheet.<init>(MappingWorksheet.java:318)
at hudson.model.Queue.maintain(Queue.java:1355)
at hudson.model.Queue$MaintainTask.doRun(Queue.java:2435)
at hudson.triggers.SafeTimerTask.run(SafeTimerTask.java:51)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:317)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:150)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:98)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:204)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)

This build was functional before upgrading Jenkins.