SOLR-4640: CachingDirectoryFactory not closed at times

[Anshum Gupta]

Hi,

I saw this JIRA [https://issues.apache.org/jira/browse/SOLR-4640] but all
it mentions is about adding a stress test. I just wanted to confirm if
there was a 'fix' that went in as well.

-- 

Anshum Gupta
http://www.anshumgupta.net