Error KeyError: ('talk.models', '', 'popularity_threshold')

```
What steps will reproduce the problem?
1. Created group/setting in module. Code below:

class NotiOptions(dbsettings.Group):
noti_sender_name = dbsettings.StringValue('notification sender name.')
noti_sender_email = dbsettings.StringValue('notification sender email.')
2. Runs dev server using python manage.py runserver .... command

What is the expected output? What do you see instead?
Program to run

What version of the product are you using? On what operating system?
Latest, current, downloaded from git

Please provide any additional information below.
Full error:

Validating models...
Unhandled exception in thread started by
Traceback (most recent call last):
File "/usr/lib/pymodules/python2.6/django/core/management/commands/runserver.py", line 48, in inner_run
self.validate(display_num_errors=True)
File "/usr/lib/pymodules/python2.6/django/core/management/base.py", line 249, in validate
num_errors = get_validation_errors(s, app)
File "/usr/lib/pymodules/python2.6/django/core/management/validation.py", line 28, in get_validation_errors
for (app_name, error) in get_app_errors().items():
File "/usr/lib/pymodules/python2.6/django/db/models/loading.py", line 146, in get_app_errors
self._populate()
File "/usr/lib/pymodules/python2.6/django/db/models/loading.py", line 61, in _populate
self.load_app(app_name, True)
File "/usr/lib/pymodules/python2.6/django/db/models/loading.py", line 78, in load_app
models = import_module('.models', app_name)
File "/usr/lib/pymodules/python2.6/django/utils/importlib.py", line 35, in import_module
__import__(name)
File "/home/python/python/django/publisy/talk/models.py", line 74, in
class Talk(models.Model):
File "/home/python/python/django/publisy/talk/models.py", line 100, in Talk
options = NotiOptions()
File "/home/python/python/django/publisy/dbsettings/group.py", line 57, in __new__
register_setting(attr)
File "/home/python/python/django/publisy/dbsettings/loading.py", line 64, in register_setting
_settings.insert(setting.key, bisect(list(_settings), setting), setting)
File "/home/python/python/django/publisy/dbsettings/loading.py", line 17, in insert
self[key] = value
File "/usr/lib/pymodules/python2.6/django/utils/datastructures.py", line 113, in __setitem__
if key not in self:
File "/home/python/python/django/publisy/dbsettings/loading.py", line 24, in __contains__
for v in self.values():
File "/usr/lib/pymodules/python2.6/django/utils/datastructures.py", line 152, in values
return map(self.__getitem__, self.keyOrder)
KeyError: ('talk.models', '', 'popularity_threshold')

```

Original issue reported on code.google.com by `krishna....@gmail.com` on 16 Sep 2011 at 6:19

Reproduce the failure with `python manage.py runserver`, then trace the KeyError from `talk/models.py` through `dbsettings/group.py` and `dbsettings/loading.py`. Done means model validation completes without the reported `('talk.models', '', 'popularity_threshold')` KeyError.

Written by the indexing model from the issue text.