## 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
hash_key = "%s.%s" % (self.feature_flag.key, self.distinct_id)
        hash_val = int(hashlib.sha1(hash_key.encode("utf-8")).hexdigest()[:15], 16)
        return hash_val / __LONG_SCALE__
def get_active_feature_flags(team: Team, distinct_id: str) -> List[str]:
    flags_enabled = []
    feature_flags = FeatureFlag.objects.filter(team=team, active=True, deleted=False).only(
        "id", "team_id", "filters", "key", "rollout_percentage"
    )
    for feature_flag in feature_flags:
        try:
            
            if feature_flag.distinct_id_matches(distinct_id):
                flags_enabled.append(feature_flag.key)
        except Exception as err:
            capture_exception(err)
    return flags_enabled