Comparison breaks on reruns

[donkirkby]

I'm not sure exactly how to reproduce it, but I reran a run, and got this error:

Traceback:

File "/opt/venv_kive/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
  34.             response = get_response(request)

File "/opt/venv_kive/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  115.                 response = self.process_exception_by_middleware(e, request)

File "/opt/venv_kive/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  113.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/opt/venv_kive/lib/python3.6/site-packages/django/views/generic/base.py" in view
  71.             return self.dispatch(request, *args, **kwargs)

File "/opt/venv_kive/lib/python3.6/site-packages/django/utils/decorators.py" in _wrapper
  45.         return bound_method(*args, **kwargs)

File "/opt/venv_kive/lib/python3.6/site-packages/django/contrib/auth/decorators.py" in _wrapped_view
  21.                 return view_func(request, *args, **kwargs)

File "/opt/venv_kive/lib/python3.6/site-packages/django/views/generic/base.py" in dispatch
  97.         return handler(request, *args, **kwargs)

File "/usr/local/share/Kive/kive/container/views.py" in get
  331.         return super(ContainerRunUpdate, self).get(request, *args, **kwargs)

File "/opt/venv_kive/lib/python3.6/site-packages/django/views/generic/edit.py" in get
  190.         return super().get(request, *args, **kwargs)

File "/opt/venv_kive/lib/python3.6/site-packages/django/views/generic/edit.py" in get
  133.         return self.render_to_response(self.get_context_data())

File "/usr/local/share/Kive/kive/container/views.py" in get_context_data
  300.             data_entries = [dict(**c._asdict()) for c in dataset_comparisons]

File "/usr/local/share/Kive/kive/container/views.py" in <listcomp>
  300.             data_entries = [dict(**c._asdict()) for c in dataset_comparisons]

Exception Type: AttributeError at /container_runs/153074/
Exception Value: 'NoneType' object has no attribute '_asdict'

One guess is that both the original and the rerun were still running when I got the error.