I'd like to suggest switching to using `/etc/sudoers.d/vagrant`:

```
( cat <<'EOP'
Defaults exempt_group=vagrant
%vagrant ALL=NOPASSWD:ALL
EOP
) > /etc/sudoers.d/vagrant
chmod 0440 /etc/sudoers.d/vagrant
```

We manage sudoers with chef and this lets us continue to use vagrant without having to make changes to our chef configs.