`\only` doesn't work any more

\only used to work, I use it a lot in my slides. Now chirun doesn't display the \only content and, weirdly, eats the next frame title too. What used to happen was that all the \only content would be displayed one thing after another in the HTML version.

Here's an example:

\documentclass{beamer}
\begin{document}
    \begin{frame}{Start}
        \begin{itemize}
            \item Hello.\pause
            \item So \textbackslash pause works
        \end{itemize}
    \end{frame}

    \begin{frame}{Middle bit uses \textbackslash only}
        \begin{itemize}
            \only<1>{\item This.}
            \only<2>{\item And that.}
        \end{itemize}
    \end{frame}

    \begin{frame}{Secret heading you won't see}
        \begin{itemize}
            \item Goodbye.
        \end{itemize}
    \end{frame}
\end{document}

In PDF, this does five slides like this:

pdf-output

The HTML version looks like this:

What I would expect to see in the HTML version is this:

(The content is missing from the HTML Slides version in the same way.)

chirun-ncl / chirun

`\only` doesn't work any more #181