Fix access to Secure HDFS

core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala

@@ -132,6 +132,8 @@ class HadoopRDD[K, V](
 
   override def getPartitions: Array[Partition] = {
     val jobConf = getJobConf()
+    // add the credentials here as this can be called before SparkContext initialized
+    SparkHadoopUtil.get.addCredentials(jobConf)
     val inputFormat = getInputFormat(jobConf)
     if (inputFormat.isInstanceOf[Configurable]) {
       inputFormat.asInstanceOf[Configurable].setConf(jobConf)