Remove RDD.coalesce default arguments.

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

@@ -235,8 +235,7 @@ abstract class RDD[T: ClassManifest](
   /**
    * Return a new RDD that is reduced into `numSplits` partitions.
    */
-  def coalesce(numSplits: Int = sc.defaultParallelism): RDD[T] =
-    new CoalescedRDD(this, numSplits)
+  def coalesce(numSplits: Int): RDD[T] = new CoalescedRDD(this, numSplits)
 
   /**
    * Return a sampled subset of this RDD.

core/src/main/scala/spark/api/java/JavaRDDLike.scala

@@ -130,11 +130,6 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends PairFlatMapWorkaround
     JavaPairRDD.fromRDD(rdd.cartesian(other.rdd)(other.classManifest))(classManifest,
       other.classManifest)
 
-  /**
-   * Return a new RDD that is reduced into the default number of partitions.
-   */
-  def coalesce(): RDD[T] = coalesce(rdd.context.defaultParallelism)
-
   /**
    * Return a new RDD that is reduced into `numSplits` partitions.
    */