Grinder tests sometimes fail with EOF exception

[hrj]

Exception in thread "main" java.io.EOFException
    at java.io.DataInputStream.readInt(DataInputStream.java:392)
    at grinder.GngrDriver.grinder$GngrDriver$$getConfirmationAndSendAck(GngrDriver.scala:212)
    at grinder.GngrDriver$$anon$4$$anonfun$to$1.apply(GngrDriver.scala:175)
    at grinder.GngrDriver$$anon$4$$anonfun$to$1.apply(GngrDriver.scala:172)
    at grinder.GngrDriver.grinder$GngrDriver$$execute(GngrDriver.scala:145)
    at grinder.GngrDriver$$anon$4.to(GngrDriver.scala:172)
    at grinder.Grinder.navigateToPage(Grinder.scala:47)
    at grinder.Grinder.grinder$Grinder$$navAndSnap(Grinder.scala:179)
    at grinder.Grinder.run(Grinder.scala:75)
    at grinder.Boot$.compare(Boot.scala:51)
    at grinder.Boot$.delayedEndpoint$grinder$Boot$1(Boot.scala:23)
    at grinder.Boot$delayedInit$body.apply(Boot.scala:6)
    at scala.Function0$class.apply$mcV$sp(Function0.scala:34)
    at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12)
    at scala.App$$anonfun$main$1.apply(App.scala:76)
    at scala.App$$anonfun$main$1.apply(App.scala:76)
    at scala.collection.immutable.List.foreach(List.scala:381)
    at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:35)
    at scala.App$class.main(App.scala:76)
    at grinder.Boot$.main(Boot.scala:6)
    at grinder.Boot.main(Boot.scala)