On 26/04/2009, at 7:52 PM, Heiko Oberdiek wrote:

> I think, a little more robust is, but longer is:
> % Version H:
> \def\in@#1#2{%
<snip the good part>

A thanks backwards though time, Heiko, for your insightful analysis  
and clever code.

This change has now been committed to the LaTeX2e SVN repository:

Furthermore, the test suite still appears to be working (which I never  
doubted for a second).

Sorry for the delay,