Flatten({()} returns no column, is this a bug or a feature?

[Jonathan Coveney]

Imagine thing is just a file with 1\n2\n3\n4\n5

a = load 'thing' as (a:int); b = foreach (group a all) generate a, a as b;
c = foreach b generate FLATTEN(a) as a, FLATTEN({()}) ; dump c;

This will return

(1)
(2)
(3)
(4)
(5)

The schema is unknown (perhaps an issue in and of itself).

It FEELS like it should be:

(1,)
(2,)
(3,)
(4,)
(5,)

but I thought I'd get opinions. I have a patch that can do this, I'm just
not sure if it's the desired outcome!