breqn is incompatible with unicode-math

[intractabilis]

Consider the following document:

\documentclass[english, 12pt, letterpaper]{scrartcl}

\usepackage{breqn}
\usepackage{unicode-math}

\begin{document}
\begin{dmath}
    T \left(h\right)
\end{dmath}

\end{document}

It results in "Missing \endgroup inserted" error. If you look at this 2009 document, it says: "Unicode is difficult, but don't worry, it’s already been done in the development version".

So, is this a bug or a feature?

[intractabilis]

Is there any hope?