Demo add dataset throws error if tags are empty

[aron.carroll]

1. Go to new dataset
2. Add a slug
3. Click next

Get error.

URL: http://localhost:5000/dataset/new
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/weberror/evalexception.py', line 431 in respond
  app_iter = self.application(environ, detect_start_response)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/webob/dec.py', line 147 in __call__
  resp = self.call_func(req, *args, **self.kwargs)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/webob/dec.py', line 208 in call_func
  return self.func(req, *args, **kwargs)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/fanstatic/publisher.py', line 234 in __call__
  return request.get_response(self.app)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/webob/request.py', line 1053 in get_response
  application, catch_exc_info=False)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/webob/request.py', line 1022 in call_application
  app_iter = application(self.environ, start_response)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/webob/dec.py', line 147 in __call__
  resp = self.call_func(req, *args, **self.kwargs)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/webob/dec.py', line 208 in call_func
  return self.func(req, *args, **kwargs)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/fanstatic/injector.py', line 52 in __call__
  response = request.get_response(self.app)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/webob/request.py', line 1053 in get_response
  application, catch_exc_info=False)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/webob/request.py', line 1022 in call_application
  app_iter = application(self.environ, start_response)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/beaker/middleware.py', line 73 in __call__
  return self.app(environ, start_response)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/beaker/middleware.py', line 152 in __call__
  return self.wrap_app(environ, session_start_response)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/routes/middleware.py', line 130 in __call__
  response = self.app(environ, start_response)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/pylons/wsgiapp.py', line 125 in __call__
  response = self.dispatch(controller, environ, start_response)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/pylons/wsgiapp.py', line 324 in dispatch
  return controller(environ, start_response)
File '/Users/Aron/.virtualenvs/ckan/src/ckan/ckan/lib/base.py', line 258 in __call__
  res = WSGIController.__call__(self, environ, start_response)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/pylons/controllers/core.py', line 221 in __call__
  response = self._dispatch_call()
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/pylons/controllers/core.py', line 172 in _dispatch_call
  response = self._inspect_call(func)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/pylons/controllers/core.py', line 107 in _inspect_call
  result = self._perform_call(func, args)
File '/Users/Aron/.virtualenvs/ckan/lib/python2.7/site-packages/pylons/controllers/core.py', line 60 in _perform_call
  return func(**args)
File '/Users/Aron/.virtualenvs/ckan/src/ckan/ckan/controllers/package.py', line 422 in new
  return self._save_new(context)
File '/Users/Aron/.virtualenvs/ckan/src/ckan/ckan/controllers/package.py', line 703 in _save_new
  return self.new(data_dict, errors, error_summary)
File '/Users/Aron/.virtualenvs/ckan/src/ckan/ckan/controllers/package.py', line 430 in new
  data['tag_string'] = ', '.join(h.dict_list_reduce(c.pkg_dict['tags'], 'name'))
TypeError: string indices must be integers, not str