Fixed the flaky unpersist test in RDDSuite.

core/src/test/scala/spark/RDDSuite.scala

@@ -106,9 +106,9 @@ class RDDSuite extends FunSuite with LocalSparkContext {
     sc = new SparkContext("local", "test")
     val rdd = sc.makeRDD(Array(1, 2, 3, 4), 2).cache()
     rdd.count
-    assert(sc.persistentRdds.isEmpty == false)
+    assert(sc.persistentRdds.isEmpty === false)
     rdd.unpersist()
-    assert(sc.persistentRdds.isEmpty == true)
+    assert(sc.persistentRdds.isEmpty === true)
 
     failAfter(Span(3000, Millis)) {
       try {
@@ -116,12 +116,12 @@ class RDDSuite extends FunSuite with LocalSparkContext {
           Thread.sleep(200)
         }
       } catch {
-        case e: Exception =>
+        case _ => { Thread.sleep(10) }
           // Do nothing. We might see exceptions because block manager
           // is racing this thread to remove entries from the driver.
       }
     }
-    assert(sc.getRDDStorageInfo.isEmpty == true)
+    assert(sc.getRDDStorageInfo.isEmpty === true)
   }
 
   test("caching with failures") {