I'm not sure what's going on here. This is the only person reporting on Mac builds so far, and the error is always the same. I'm not sure if the problem is due to a strange setup on this person's machine, or if it's a more general problem.
A particular surprise is that we're passing on an OS that describes itself as "Debian GNU/kFreeBSD". Never heard of that!. Anyway, I'll keep everyone posted as I refine the recipe.
-- "Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." -- Brian Kernighan