The 6560126 fix includes a change to throw all Errors from ClassLoader, which caused a behavior change. When there are a class and a properties file which have the same bundle name in different case, such as "Config.class" and "config.properties", a class loader throws "java.lang.NoClassDefFoundError: config (wrong name: Config)" on Windows. Previously this Error was ignored in ResourceBundle.getBundle and "config.properties" was loaded successfully. However, ResourceBundle.getBundle fails to load the properties file after the 6560126 change.
There's no problem on UNIX/Linux.