makeinfo --docbook bug with index

[arnold]

Hi.

In docbook output, given something like this input:

        ....
        @node Concept Index
        @unnumbered Index

        @printindex cp

        @bye

The generated docbook is

        ....
        </chapter>
        <chapter label="" id="Concept-Index">
        <title>Index</title>

        <index role="cp"></index>

        </chapter>
        </book>

This isn't valid docbook. It should be

        ....
        </chapter>

        <index role="cp"></index>

        </book>

The <index> tag could be

        <index role="cp"/>

but that is a minor quibble.

Removing the @node and @unnumbered don't help, then we get the
<index> tag before the </chapter> tag and it needs to come after it.

Thanks!

Arnold