I have an OutputFormat which implements Configurable. I set new config entries to a job configuration during checkOutputSpec() so that the tasks will get the config entries through the job configuration. This works fine in 0.20.2, but stopped working starting from 0.20.203. With 0.20.203, my OutputFormat still has the configuration set, but the copy a task gets does not have the new entries that are set as part of checkOutputSpec().
I believe that the problem is with JobClient. The job configuration needs to wait till checkOutputSpec() is returned before being cloned and submitted.