private IOException convertThrowableToIOE(final Throwable t, final String msg) {
    return (t instanceof IOException ? (IOException) t
      : msg == null || msg.length() == 0 ? new IOException(t)
      : new IOException(msg, t));
  }
@param msg Message to put in new IOE if passed <code>t</code> is not an IOE
@return Make <code>t</code> an IOE if it isn't already.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java