Problem of Spark with FunSuite and defaultParallelism

build.sbt

name := "Fun Suite Test"

scalaVersion := "2.10.4"

libraryDependencies ++= Seq(
    "org.apache.spark" % "spark-core_2.10" % "1.0.2"
  , "org.scalatest"    % "scalatest_2.10"  % "2.2.2"
  )

MyTestSuite.scala

import org.scalatest.FunSuite

import org.apache.spark.SparkConf
import org.apache.spark.SparkContext


class MyTestSuite extends FunSuite {

  val conf = new SparkConf()
                     .setAppName("My Spark test")
                     .setMaster("local")
                     .set("spark.default.parallelism","1")
  val sc = new SparkContext(conf)
  try {
    this.test("My Spark test") {
      sc.parallelize(Seq(1,2,3)) // crashes
      //sc.parallelize(Seq(1,2,3),4) // doesn't crash
    }
  } finally {
    sc.stop
  }
}