{align} with {tabular}

[dginev]

We are quietly producing broken output when a {tabular} is used inside {align}.

This may have to do with some fragility between the <MathFork> and alignment mechanisms?

A minimal example:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align}
  \left(\begin{tabular}{ccc}
       -1&0&0  \\
       0&-1&0  \\
       0&0&1  \\
  \end{tabular}\right)
\end{align}
\end{document}

Today's rendering:

Originally reported in arXiv/html_feedback#2675