The ETLMapReduceTest testDAGSchemaChanges seems to be flaky.
We have noticed this failure earlier and it started passing on its own. I ran the test class from my machine on the cluster two times and it passed.
Recent failure was here: http://builds.cask.co/browse/CDAP-ITN13-26
I did a run on the whole suite through custom cluster which was successful here: http://builds.cask.co/browse/CDAP-ITCC10-21
This happened on HDP 2.0 in the above build link. I remember seeing it fail randomly on HDP 2.2 too.