regression: ESS cannot be compiled

[Gavin Smith]

>     > I have reduced the problematic case to the following minimal example:

Thank you for taking the time to do this, Norbert.

> From these two facts I'd declare that the new texinfo.tex that
> you have in Debian is broken.
> (Yes, that is a strong statement; but still breaking something
>  that worked dozens of year w/o problems needs VERY good arguments
>  before you can call it "progress" !!)

No-one's said that breaking this usage is progress. It wasn't intended
and we will fix it.

The problem comes from trying to support the Texinfo macro facility,
the different ways that it's been used in different documents and
managing multiple incompatible implementations of it. It's caused
problems ever since it was introduced, maybe about 20 years ago.
Evidently these problems aren't at an end yet, despite hope. When the
fix is finalized I'll add this breaking usage to our test file to
prevent it breaking again.