Periodic tasks not working

I can't seem to get the periodic tasks to execute, or show up in the 'scheduled' queue.

Using the following tasks.py for debug:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
import redis
from tasktiger import TaskTiger
from tasktiger.schedule import periodic

tiger = TaskTiger()


@tiger.task(schedule=periodic(seconds=1), queue='periodic')
def periodic_task():
    """Periodic task."""
    conn = redis.Redis(decode_responses=True)
    conn.incr('period_count', 1)


@tiger.task()
def test_task():
    """Minimal task."""
    print('Hello')

Running tasktiger as shown in docs:

$ PYTHONPATH=. tasktiger

I can run the minimal test_task:

>>> import tasks
>>> tasks.test_task.delay()
<Task <function test_task at 0x7f03aaacfd08>>

I see the output in the log, but there is no evidence of the periodic_task and the redis key 'period_count' never increments:

{"pid": 27295, "queues": [], "exclude_queues": [], "single_worker_queues": [], "event": "ready", "level": "info", "timestamp": "2017-10-26T12:43:35.236665Z"}
{"pid": 27295, "queue": "default", "event": "new queue", "level": "debug", "timestamp": "2017-10-26T12:44:09.818470Z"}
{"pid": 27295, "queue": "default", "src_queue": "queued", "dest_queue": "active", "qty": 1, "event": "moved tasks", "level": "debug", "timestamp": "2017-10-26T12:44:09.819402Z"}
{"pid": 27295, "queue": "default", "child_pid": 27318, "func": "tasks:test_task", "task_id": "c44b198caac44250d06fc5dfc3249960d9eb5bfbe76d8bb848ddb419c8382323", "params": {"args": [], "kwargs": {}}, "event": "processing", "level": "info", "timestamp": "2017-10-26T12:44:09.820179Z"}
Hello
{"pid": 27295, "queue": "default", "attempted": 1, "processed": 1, "event": "processed", "level": "debug", "timestamp": "2017-10-26T12:44:09.823499Z"}
{"pid": 27295, "queue": "default", "task_id": "c44b198caac44250d06fc5dfc3249960d9eb5bfbe76d8bb848ddb419c8382323", "event": "done", "level": "info", "timestamp": "2017-10-26T12:44:09.825171Z"}
{"pid": 27295, "queue": "default", "src_queue": "queued", "dest_queue": "active", "qty": 0, "event": "moved tasks", "level": "debug", "timestamp": "2017-10-26T12:44:09.825592Z"}
{"pid": 27295, "time_total": 60.00032615661621, "time_busy": 0.003787517547607422, "utilization": 0.006312494931645924, "event": "stats", "level": "info", "timestamp": "2017-10-26T12:44:35.237246Z"}

Am I missing something?

By the way, TaskTiger is a great project!

Start with the provided tasks.py reproduction and the tasktiger command entry point, focusing on how schedule.periodic tasks are registered and exposed in the scheduled queue. Verify the behavior against Redis and the period_count key; the issue is resolved when periodic_task runs and the key increments as expected.