Luke makes background index changes instead of just reading it

[GoogleCodeExporter]

I had a few days of headache of debugging lucene FileNotFoundException. In the 
background I've been using LUKE 3.1.0 to view what happens in the index.

Finally it turned out that I was chasing the bug that doesn't exists. All 
because simple opening the index in LUKE, immediately makes changes to the 
index (if LUKE decides to merge the it), instead of simple reading it. 

This is really unexpected if you want just to read the index and trace changes. 
This is more unexpected if you have another application you want to debug, that 
uses IndexWriter in exclusive mode (FNFE).

Can this be turned off?

Please review https://issues.apache.org/jira/browse/LUCENE-3422

Original issue reported on code.google.com by [email protected] on 19 Jul 2013 at 9:21