private void delUpToTimestamp(String qual, long upToTS) {
    del.addColumns(FAMILY_BYTES, Bytes.toBytes(qual), upToTS);
    logDelete(qual, upToTS, "up to and including");
  }
Disable this when this test fails hopelessly and you need to debug a simpler case.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestSeekOptimizations.java