HBASE-18945 found that the comparators passed to the CellChunkImmutableSegment and CellArrayImmutableSegment are sometimes wrong. We pass the comparator that we got from the Store but when doing reinitializeCellSet we always use CellComparator.COMPARATOR.
From code I don think we are stopping the META region to also go through CompactingMemstore. If we do that then this JIRA is invalid. But considering that is not the case we should fix it and pass the right comparator.