title: repartition() is not affecting RDD partition size
body: <p>I am trying to change partition size of an RDD using repartition() method. The method call on the RDD succeeds, but when I explicitly check the partition size using partition.size property of the RDD, I get back the same number of partitions that it originally had:-</p>
  
  <pre><code>scala&gt; rdd.partitions.size
  res56: Int = 50
  
  scala&gt; rdd.repartition(10)
  res57: org.apache.spark.rdd.RDD[String] = MapPartitionsRDD[19] at repartition at &lt;console&gt;:27
  </code></pre>
  
  <p>At this stage I perform some action like rdd.take(1) just to force evaluation, just in case if that matters. And then I again check the partition size:-</p>
  
  <pre><code>scala&gt; rdd.partitions.size
  res58: Int = 50
  </code></pre>
  
  <p>As one can see, it's not changing. Can someone answer why? </p>