[m-rev.] for review: remove "is" as synonym for "="

[Julien Fischer]

On Fri, 21 Aug 2020, Zoltan Somogyi wrote:

> For review by anyone. The second part will be committed
> after the first is in an rotd.

That looks fine.

> BTW, I couldn't find any actual documentation of "is"
> as a synonym for "=". It is not among the goal kinds in
> section 2.11 of the reference manual, and a search for "{is}"
> did not find anything relevant. (A search for plain "is" would
> yield far too many false hits to be useful.)

I don't think there is any such documentation.

Julien.