*  revision has been deleted, returns null.
     *  @throws IOException if a network error occurs
     *  @since 0.17
     */
    public Wiki.Revision getRevision(long oldid) throws IOException
    {
        // build url and connect
        String url = query + "prop=revisions&rvprop=ids%7Ctimestamp%7Cuser%7Ccomment%7Cflags%7Csize&revids=" + oldid;
        String line = fetch(url, "getRevision");
        // check for deleted revisions
        if (line.contains("<badrevids>"))
            return null;
        return parseRevision(line, "");
    }