Configuration tries to read from an inputstream resource multiple times.

If someone calls Configuration.addResource(InputStream) and then reloadConfiguration is called for any reason, Configruation will try to reread the contents of the InputStream, after it has already closed it.

This never showed up in 1.0 because the framework itself does not call addResource with an InputStream, and typically by the time user code starts running that might call this, all of the default and site resources have already been loaded.

In 0.23 mapreduce is now a client library, and mapred-site.xml and mapred-default.xml are loaded much later in the process.