What version are you running?
2.5.9
What's the URL of the page containing the problem?
http://reviewboard.abc.com/admin/db/scmtools/repository/3/
What steps will reproduce the problem?

login dashboard
switch to admin console
click repository 
click any repo


What is the expected output? What do you see instead?
Environment:

Request Method: GET

Request URL: http://reviewboard.56qq.com/admin/db/scmtools/repository/3/
Django Version: 1.6.11

Python Version: 2.7.6

Installed Applications:

[u'django.contrib.admin',

 u'django.contrib.auth',

 u'django.contrib.contenttypes',

 u'django.contrib.sites',

 u'django.contrib.sessions',

 u'django.contrib.staticfiles',

 u'djblets',

 u'djblets.configforms',

 u'djblets.datagrid',

 u'djblets.extensions',

 u'djblets.feedview',

 u'djblets.gravatars',

 u'djblets.log',

 u'djblets.pipeline',

 u'djblets.siteconfig',

 u'djblets.util',

 u'haystack',

 u'pipeline',

 u'reviewboard',

 u'reviewboard.accounts',

 u'reviewboard.admin',

 u'reviewboard.attachments',

 u'reviewboard.changedescs',

 u'reviewboard.diffviewer',

 u'reviewboard.extensions',

 u'reviewboard.hostingsvcs',

 u'reviewboard.notifications',

 u'reviewboard.reviews',

 u'reviewboard.scmtools',

 u'reviewboard.site',

 u'reviewboard.webapi',

 u'django_evolution']

Installed Middleware:

[u'django.middleware.gzip.GZipMiddleware',

 u'reviewboard.admin.middleware.InitReviewBoardMiddleware',

 u'django.middleware.clickjacking.XFrameOptionsMiddleware',

 u'django.middleware.common.CommonMiddleware',

 u'django.middleware.doc.XViewMiddleware',

 u'django.middleware.http.ConditionalGetMiddleware',

 u'django.middleware.locale.LocaleMiddleware',

 u'django.contrib.sessions.middleware.SessionMiddleware',

 u'django.contrib.auth.middleware.AuthenticationMiddleware',

 u'django.contrib.messages.middleware.MessageMiddleware',

 u'djblets.siteconfig.middleware.SettingsMiddleware',

 u'reviewboard.admin.middleware.LoadSettingsMiddleware',

 u'djblets.extensions.middleware.ExtensionsMiddleware',

 u'djblets.log.middleware.LoggingMiddleware',

 u'reviewboard.accounts.middleware.TimezoneMiddleware',

 u'reviewboard.admin.middleware.CheckUpdatesRequiredMiddleware',

 u'reviewboard.admin.middleware.X509AuthMiddleware',

 u'reviewboard.site.middleware.LocalSiteMiddleware',

 u'djblets.extensions.middleware.ExtensionsMiddlewareRunner',

 u'reviewboard.admin.middleware.ExtraExceptionInfoMiddleware']

Traceback:

File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py" in get_response

  112.                     response = wrapped_callback(request, callback_args, callback_kwargs)

File "/usr/local/lib/python2.7/dist-packages/django/contrib/admin/options.py" in wrapper

  465.                 return self.admin_site.admin_view(view)(*args, kwargs)

File "/usr/local/lib/python2.7/dist-packages/django/utils/decorators.py" in _wrapped_view

  99.                     response = view_func(request, args, kwargs)

File "/usr/local/lib/python2.7/dist-packages/django/views/decorators/cache.py" in _wrapped_view_func

  52.         response = view_func(request, *args, kwargs)

File "/usr/local/lib/python2.7/dist-packages/django/contrib/admin/sites.py" in inner

  198.             return view(request, args, kwargs)

File "/usr/local/lib/python2.7/dist-packages/django/utils/decorators.py" in _wrapper

  29.             return bound_func(*args, kwargs)

File "/usr/local/lib/python2.7/dist-packages/django/utils/decorators.py" in _wrapped_view

  99.                     response = view_func(request, args, kwargs)

File "/usr/local/lib/python2.7/dist-packages/django/utils/decorators.py" in bound_func

  25.                 return func(self, *args2, kwargs2)

File "/usr/local/lib/python2.7/dist-packages/django/db/transaction.py" in inner

  371.                 return func(args, *kwargs)

File "/usr/local/lib/python2.7/dist-packages/django/contrib/admin/options.py" in change_view

  1270.             form = ModelForm(instance=obj)

File "/usr/local/lib/python2.7/dist-packages/reviewboard/scmtools/forms.py" in init

  297.                                                hosting_accounts)

File "/usr/local/lib/python2.7/dist-packages/reviewboard/scmtools/forms.py" in _get_hosting_service_info

  471.                 if account.service_name == hosting_service.id

File "/usr/local/lib/python2.7/dist-packages/reviewboard/hostingsvcs/models.py" in is_authorized

  54.             return service.is_authorized()

File "/usr/local/lib/python2.7/dist-packages/reviewboard/hostingsvcs/gitlab.py" in is_authorized

  279.         return 'private_token' in self.account.data
Exception Type: TypeError at /admin/db/scmtools/repository/3/

Exception Value: argument of type 'NoneType' is not iterable
What operating system are you using? What browser?
Ubuntu 14.04.2 LTS 

Linux ub 3.16.0-30-generic
Please provide any additional information below.
NO