Interpreter produces (or at least prints) wrong value in some trivial cases

[athas]

-- ==
-- input { 2i64 }
-- output { [[0i64,1i64],[0i64,1i64]] }

def main n = replicate n (iota n)

The interpreter prints the result as one-dimensional. I have no idea how our tests currently work when something this basic is going wrong.

[athas]

It's a very recent regression.

[athas]

Was not present in latest release. Probably related to the prettyprinter fiddling I did recently.

[athas]

I think I must have screwed up something locally; this no longer occurs.