Minor Description
The test class org.apache.hadoop.mapred.TestMiniMRMapRedDebugScript catches and prints exception details then calls fail(), rather than relaying the exception up to the calling test framework. this make the full stack trace harder to obtain. It could be a relic of the class having its own main() entry point.
trivial to fix: add Exception to the test signature, move the catch/print into the main() method for that entry point