Is This a MathJax Bug?

The \shoveleft and \shoveright control sequences don't seem to work even though they're included in the documentation.

The following:

\[\begin{array}{c}\shoveleft{I}\\MMMMM\\\shoveright{I}\end{array}\]

should look like:
\begin{multline}I\\MMMMM\\I\end{multline}
(albeit more compact) but instead looks like:
\[\begin{array}{c}\shoveleft{I}\\MMMMM\\\shoveright{I}\end{array}\]