Bug: Wrong alignment of patterns

On `master` with `--align-cases`:

```ocaml
let _ =
  match (foooooooooooooo, foooooooooooooo) with
  | Some a, Some b -> a + b
  | None, _            -> 1
  | Some _, None     -> 2
```

Arrows are not aligned.

An other example:

```ocaml
let _ =
  match (foooooooooooooo, foooooooooooooo) with
  | [x]           -> x
  | [_; x] -> x
  | _                    -> 0
```
