SOLR-2500 because TestSolrProperties is failing consistently on Windows 7/Oracle JDK 1.6.0_21 for me, but it appears that this is the issue that introduced the problem.
I've tracked the issue down to the anonymous FileInputStream created in order to print out the contents of the persisted core configuration to STDOUT – the following line was uncommented when Mark committed the patch on this issue:
206: System.out.println(IOUtils.toString(new FileInputStream(new File(solrXml.getParent(), "solr-persist.xml"))));
This patch de-anonymizes the FileInputStream and closes it after the file contents are printed out.
I plan to commit this later tonight.