promise.then(reply) not working

So I've thought I should be able to do something like the following

```javascript
omelette`bin ${({reply}) => Promise.resolve(["a","b"]).then(reply)`
```

but for some reason this doesn't work, can you help me? Replying immediately works, returning the options array also works. But promises don't work in this way, even though it seems to be the exact same usage as in the readme.