## 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
import hashlib
from typing import Any, Dict, List
from django.contrib.postgres.fields import JSONField
from django.db import models
from django.db.models.expressions import ExpressionWrapper, RawSQL
from django.db.models.fields import BooleanField
from django.db.models.query import QuerySet
from django.utils import timezone
from sentry_sdk.api import capture_exception
from posthog.models.filters.mixins.utils import cached_property
from posthog.models.team import Team
from posthog.queries.base import properties_to_Q
from .filters import Filter
from .person import Person
__LONG_SCALE__ = float(0xFFFFFFFFFFFFFFF)
class FeatureFlag(models.Model):