## Bug description

This is what a default feature flag looks like:
<img width="577" alt="empty feature flag" src="https://user-images.githubusercontent.com/4550621/113333154-63f36a00-9322-11eb-8fb0-71b0cd865181.png">
It has no rollout percentage specified, nor filters, so it says "Rolling out to 100% of users". However I've experienced that in fact in this situation the flag is rolled out to *nobody*.

CC @paolodamico 

## Expected behavior

Flag should work the way it says.

## How to reproduce

1. Create a feature flag and leave it as is, supposedly completely rolled out.
2. Try to use it.
3. Discover that the flag is not rolled out.

## Environment

- [x] PostHog Cloud
- [x] self-hosted PostHog, version/commit: master (8f4ae2b)

#### *Thank you* for your bug report – we love squashing them!

posthog/models/feature_flag.py
return len(self.query_groups) > 0 and self.query_groups[0][group_index]
    @cached_property
    def query_groups(self) -> List[List[bool]]:
        query: QuerySet = Person.objects.filter(
            team_id=self.feature_flag.team_id,
            persondistinctid__distinct_id=self.distinct_id,
            persondistinctid__team_id=self.feature_flag.team_id,
        )
        fields = []
        for index, group in enumerate(self.feature_flag.groups):
            key = f"group_{index}"
            if len(group.get("properties", {})) > 0:
                expr: Any = properties_to_Q(
                    Filter(data=group).properties, team_id=self.feature_flag.team_id, is_person_query=True
                )
            else:
                expr = RawSQL("true", [])
            query = query.annotate(**{key: ExpressionWrapper(expr, output_field=BooleanField())})
            fields.append(key)
        return list(query.values_list(*fields))
    
    
    
    
    @cached_property
    def _hash(self) -> float: