Issues with optional parameters in \newcommand

[ArcheCraft]

In this example

$\newcommand{\plim}[1][n]{\lim\limits_{#1\to\infty}}$
$\plim[x] a_n$
$\plim{x} a_n$
$\plim a_n$

I would expect the \plim usage to not remove the next char after it. It seems like the parser is having issues with commands with optional parameters.

[NanoMichael]

fixed by 4383f55