up to hadoop 0.18.3 org.apache.hadoop.mapred.JobShell ensured that 'hadoop jar' returns non-zero exit code when the job fails.
This is no longer true after moving this to org.apache.hadoop.util.RunJar.
Pipes jobs submitted through cli never returned proper exit code.
The main methods in org.apache.hadoop.util.RunJar. and org.apache.hadoop.mapred.pipes.Submitter should be modified to return an exit code similar to how org.apache.hadoop.mapred.JobShell did it.