fix for https://spark-project.atlassian.net/browse/SPARK-1052

Author: Bijay Bisht <bijay.bisht@gmail.com>

Closes #568 from bijaybisht/SPARK-1052 and squashes the following commits:

da70395 [Bijay Bisht] fix for https://spark-project.atlassian.net/browse/SPARK-1052 - comments incorporated
fdb1d94 [Bijay Bisht] fix for https://spark-project.atlassian.net/browse/SPARK-1052



(cherry picked from commit e797c1ab)
Signed-off-by: Aaron Davidson <aaron@databricks.com>