Milestone #6691: Improve error reporting in client
Need user friendly message if job exe is not found
If the client cannot find job exe it raises an exception. Though this is good for debugging, clients should not see the exceptions otherwise. We should wrap the errors/exceptions cleanly, print helpful message and exit.
if not os.path.exists(self.jobExe): err="file %s not found. Exiting" % self.jobExe raise JobSubClientError(err)