JobSubmitter#checkSpecs doesn not handle the situation when reduceNums is set less than zero.

private void checkSpecs(Job job) throws ClassNotFoundException,
	InterruptedException, IOException {
	JobConf jConf = (JobConf)job.getConfiguration();
	// Check the output specification
	if (jConf.getNumReduceTasks() == 0 ?
	jConf.getUseNewMapper() : jConf.getUseNewReducer()) {
	org.apache.hadoop.mapreduce.OutputFormat<?, ?> output =
	ReflectionUtils.newInstance(job.getOutputFormatClass(),
	job.getConfiguration());
	output.checkOutputSpecs(job);
	} else {
	jConf.getOutputFormat().checkOutputSpecs(jtFs, jConf);
	}
	}