IndexReader.reopen issue

[Jason Rutherglen]

When this code is run, why are the generation numbers the same?  The desired
behavior is that the delete happens only to the newIndexReader, leaving the
previousIndexReader unaffected.

IndexReader previousIndexReader = latestIndexSnapshot.getIndexReader();
IndexReader newIndexReader = previousIndexReader.reopen(); // returns the
same reader?
newIndexReader.deleteDocument(10);
newIndexReader.flush();
newIndexReader = newIndexReader.reopen();
LOG.info("previous reader gen:
"+previousIndexReader.getIndexCommit().getGeneration()+" newIndexReader gen:
"+newIndexReader.getIndexCommit().getGeneration());