SC2129 - If there is already a grouped redirection, SC2129 cannot be triggered

The following *problematic* code does **not** trigger [SC2129](https://www.shellcheck.net/wiki/SC2129) — if there is already a grouped redirection, [SC2129](https://www.shellcheck.net/wiki/SC2129) cannot be triggered:

```bash
{
  echo foo
  date
} >> file
cat stuff >> file
```

Correct code:
```bash
{
  echo foo
  date
  cat stuff
} >> file
```
