Fix are/our typo.

core/src/main/scala/spark/RDD.scala

@@ -240,7 +240,7 @@ abstract class RDD[T: ClassManifest](
    */
   def coalesce(numPartitions: Int, shuffle: Boolean = false): RDD[T] = {
     if (shuffle) {
-      // include a shuffle step so that are upstream tasks are still distributed
+      // include a shuffle step so that our upstream tasks are still distributed
       new CoalescedRDD(new ShuffledRDD(map(x => (x, null)), new HashPartitioner(numPartitions)), numPartitions).keys
     } else {
       new CoalescedRDD(this, numPartitions)