Fix flaky test by changing catch and adding sleep

core/src/test/scala/spark/DistributedSuite.scala

@@ -261,9 +261,9 @@ class DistributedSuite extends FunSuite with ShouldMatchers with BeforeAndAfter
     val data = sc.parallelize(Seq(true, false, false, false), 4)
     data.persist(StorageLevel.MEMORY_ONLY_2)
     data.count
-    assert(sc.persistentRdds.isEmpty == false)
+    assert(sc.persistentRdds.isEmpty === false)
     data.unpersist()
-    assert(sc.persistentRdds.isEmpty == true)
+    assert(sc.persistentRdds.isEmpty === true)
 
     failAfter(Span(3000, Millis)) {
       try {
@@ -271,12 +271,12 @@ class DistributedSuite extends FunSuite with ShouldMatchers with BeforeAndAfter
           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)
   }
 }