@VisibleForTesting
    public void cleanupTmpLocationOnTaskRetry(AcidOutputFormat.Options options, Path rootDir) throws IOException {
      Path tmpLocation = AcidUtils.createFilename(rootDir, options);
      FileSystem fs = tmpLocation.getFileSystem(jobConf);

      try {
        fs.delete(tmpLocation, true);
      } catch (FileNotFoundException e) {
        // no problem
      }
    }
This input format returns its own input split as a value.  This is because our splits
contain information needed to properly construct the writer.  Crazy, huh?
ql/src/java/org/apache/hadoop/hive/ql/txn/compactor/MRCompactor.java