Bug reports.

Well, if you were editing the map anyway, it would be easier to give the player a town portal in some other way. Or allow this spell on the map, but prohibit it in towns and remove random scrolls, random mages, etc. Or find the original version of the map (which hasn't been converted to the "Horn of the Abyss" format yet).

I don't remember which version it appeared in, but it was a long time ago, and it's unlikely that you'll be able to easily find such an old version.