\alignat and \alignedat spacing with relations

Created by: orangeplanet

When using \alignat or \alignedat, if the first marker (&) is set on =, <, >, \le, \ge, etc., then the space to the left of the relation disappears. Example:

$$
\begin{alignat}{2}
-\nabla\cdot(\alpha(x,\nabla u)\nabla u)&=f(x)&&\quad{\rm in}\
\Omega\subset \Bbb R^2,\\
u&=0&&\quad{\rm on}\ \partial\Omega,
\end{alignat}
$$

Tested with Firefox 28, using MathJax 2.3 and 2.4 beta.