Celery keep firing task every 5 minutes if I use crontab

Question

Celery keep firing task every 5 minutes if I use crontab.

I have django project with requirements:

Python3.4
celery==3.1.17
Django==1.8

And I have follow options in settings.py

from celery.schedules import crontab

USE_TZ = True
TIME_ZONE = 'Europe/Moscow'

CELERY_ENABLE_UTC = False
CELERY_TIMEZONE = TIME_ZONE

CELERYBEAT_SCHEDULE = {
    'every-day': {
        'task': 'app.tasks.every_day',
        'schedule': crontab(minute=30, hour=0),
    },
}

Celery works under supervisord:

celery worker -A proj -l info --concurrency=2 -Ofair
celery beat -A proj  -l info

After 00:30 at midnight Celery sends task first time and then keep firing it until 03:30.

I found issue on github with similar symptoms, but it didn't help.