Merge pull request #1900 from k9mail/fix_format_string_bug

        }

        // Get the extension of the file, if any.

        int index = filename.lastIndexOf('.');

        String format;

        String name;

        String extension;

        if (index != -1) {

            String name = filename.substring(0, index);

            String extension = filename.substring(index);

            format = name + "-%d" + extension;

            name = filename.substring(0, index);

            extension = filename.substring(index);

        } else {

            format = filename + "-%d";

            name = filename;

            extension = "";

        }

        for (int i = 2; i < Integer.MAX_VALUE; i++) {

            file = new File(directory, String.format(Locale.US, format, i));

            file = new File(directory, String.format(Locale.US, "%s-%d%s", name, i, extension));

            if (!file.exists()) {

                return file;

            }