python manage.py makemigrations polls

运行它时，出现以下错误：

python manage.py makemigrations polls
Traceback (most recent call last):
  File "<frozen importlib._bootstrap>", line 2218, in_find_and_load_unlocked
AttributeError: 'module' object has no attribute '__path__'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/tgumm/pythonenv/tutorial/lib/python3.4/site-packages/django/core/management/__init__.py", line 353, in execute_from_command_line
utility.execute()
  File "/home/tgumm/pythonenv/tutorial/lib/python3.4/site-packages/django/core/management/__init__.py", line 327, in execute
django.setup()
  File "/home/tgumm/pythonenv/tutorial/lib/python3.4/site-packages/django/__init__.py", line 18, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/home/tgumm/pythonenv/tutorial/lib/python3.4/site-packages/django/apps/registry.py", line 85, in populate
app_config = AppConfig.create(entry)
  File "/home/tgumm/pythonenv/tutorial/lib/python3.4/site-packages/django/apps/config.py", line 116, in create
mod = import_module(mod_path)
  File "/home/tgumm/pythonenv/tutorial/lib/python3.4/importlib/__init__.py", line 109, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 2254, in _gcd_import
  File "<frozen importlib._bootstrap>", line 2237, in _find_and_load
  File "<frozen importlib._bootstrap>", line 2212, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 321, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 2254, in _gcd_import
  File "<frozen importlib._bootstrap>", line 2237, in _find_an``d_load
  File "<frozen importlib._bootstrap>", line 2221, in _find_and_load_unlocked
ImportError: No module named 'polls.apps.PollsConfigdjango'; 'polls.apps' is not a package

这是我的模型：

from django.db import models

# Create your models here.
from django.db import models


class Question(models.Model):
    question_text = models.CharField(max_length=200)
    pub_date = models.DateTimeField('date published')


class Choice(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    choice_text = models.CharField(max_length=200)
    votes = models.IntegerField(default=0)