Shutdown hooks cannot be modified during shutdown.

sbt.ForkMain$ForkError: Shutdown hooks cannot be modified during shutdown.
	at org.apache.spark.util.SparkShutdownHookManager.add(ShutdownHookManager.scala:250)
	at org.apache.spark.util.ShutdownHookManager$.addShutdownHook(ShutdownHookManager.scala:193)
	at org.apache.spark.storage.DiskBlockManager.addShutdownHook(DiskBlockManager.scala:147)
	at org.apache.spark.storage.DiskBlockManager.<init>(DiskBlockManager.scala:54)
	at org.apache.spark.storage.BlockManager.<init>(BlockManager.scala:76)
	at org.apache.spark.SparkEnv$.create(SparkEnv.scala:365)
	at org.apache.spark.SparkEnv$.createDriverEnv(SparkEnv.scala:193)
	at org.apache.spark.SparkContext.createSparkEnv(SparkContext.scala:288)
	at org.apache.spark.SparkContext.<init>(SparkContext.scala:457)
	at org.apache.spark.HeartbeatReceiverSuite.beforeEach(HeartbeatReceiverSuite.scala:73)
	at org.scalatest.BeforeAndAfterEach$class.beforeEach(BeforeAndAfterEach.scala:154)
	at org.apache.spark.HeartbeatReceiverSuite.beforeEach(HeartbeatReceiverSuite.scala:44)
	at org.scalatest.BeforeAndAfterEach$class.beforeEach(BeforeAndAfterEach.scala:173)
	at org.apache.spark.HeartbeatReceiverSuite.beforeEach(HeartbeatReceiverSuite.scala:44)
	at org.scalatest.BeforeAndAfterEach$class.runTest(BeforeAndAfterEach.scala:253)
	at org.apache.spark.HeartbeatReceiverSuite.runTest(HeartbeatReceiverSuite.scala:44)
	at org.scalatest.FunSuiteLike$$anonfun$runTests$1.apply(FunSuiteLike.scala:208)
	at org.scalatest.FunSuiteLike$$anonfun$runTests$1.apply(FunSuiteLike.scala:208)
	at org.scalatest.SuperEngine$$anonfun$traverseSubNodes$1$1.apply(Engine.scala:413)
	at org.scalatest.SuperEngine$$anonfun$traverseSubNodes$1$1.apply(Engine.scala:401)
	at scala.collection.immutable.List.foreach(List.scala:318)
	at org.scalatest.SuperEngine.traverseSubNodes$1(Engine.scala:401)
	at org.scalatest.SuperEngine.org$scalatest$SuperEngine$$runTestsInBranch(Engine.scala:396)
	at org.scalatest.SuperEngine.runTestsImpl(Engine.scala:483)
	at org.scalatest.FunSuiteLike$class.runTests(FunSuiteLike.scala:208)
	at org.scalatest.FunSuite.runTests(FunSuite.scala:1555)
	at org.scalatest.Suite$class.run(Suite.scala:1424)
	at org.scalatest.FunSuite.org$scalatest$FunSuiteLike$$super$run(FunSuite.scala:1555)
	at org.scalatest.FunSuiteLike$$anonfun$run$1.apply(FunSuiteLike.scala:212)
	at org.scalatest.FunSuiteLike$$anonfun$run$1.apply(FunSuiteLike.scala:212)
	at org.scalatest.SuperEngine.runImpl(Engine.scala:545)
	at org.scalatest.FunSuiteLike$class.run(FunSuiteLike.scala:212)
	at org.apache.spark.HeartbeatReceiverSuite.org$scalatest$BeforeAndAfterAll$$super$run(HeartbeatReceiverSuite.scala:44)
	at org.scalatest.BeforeAndAfterAll$class.liftedTree1$1(BeforeAndAfterAll.scala:257)
	at org.scalatest.BeforeAndAfterAll$class.run(BeforeAndAfterAll.scala:256)
	at org.apache.spark.HeartbeatReceiverSuite.run(HeartbeatReceiverSuite.scala:44)
	at org.scalatest.tools.Framework.org$scalatest$tools$Framework$$runSuite(Framework.scala:462)
	at org.scalatest.tools.Framework$ScalaTestTask.execute(Framework.scala:671)
	at sbt.ForkMain$Run$2.call(ForkMain.java:294)
	at sbt.ForkMain$Run$2.call(ForkMain.java:284)
	at java.util.concurrent.FutureTask.run(FutureTask.java:262)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)