Tracing from mid-point fails with not defined exception

[DanSheps]

Environment

• Python version: 3.7
• NetBox version: 2.10-beta1 (develop)

Steps to Reproduce

1. Create a device (switch) with a interface
2. Create a device (panel 1) with front and rear ports
3. Create another device (panel 2) with front and rear ports
4. Connect switch interface to panel 1 front port
5. Connect panel 1 rear port to panel 2 rear port
6. Go to panel 2 rear port and attempt a trace

Expected Behavior

Trace completes to switch

Observed Behavior

Trace fails

<class 'NameError'>

name 'obj' is not defined

Traceback:

Traceback (most recent call last):
  File "/usr/local/netbox/venv/lib64/python3.6/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/usr/local/netbox/venv/lib64/python3.6/site-packages/django/core/handlers/base.py", line 179, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/local/netbox/venv/lib64/python3.6/site-packages/django/views/generic/base.py", line 70, in view
    return self.dispatch(request, *args, **kwargs)
  File "/usr/local/netbox/netbox/dcim/views.py", line 2068, in dispatch
    return super().dispatch(request, *args, **kwargs)
  File "/usr/local/netbox/netbox/utilities/views.py", line 91, in dispatch
    return super().dispatch(request, *args, **kwargs)
  File "/usr/local/netbox/venv/lib64/python3.6/site-packages/django/views/generic/base.py", line 98, in dispatch
    return handler(request, *args, **kwargs)
  File "/usr/local/netbox/netbox/netbox/views/generic.py", line 70, in get
    **self.get_extra_context(request, instance),
  File "/usr/local/netbox/netbox/dcim/views.py", line 2079, in get_extra_context
    related_paths = CablePath.objects.filter(path__contains=obj).prefetch_related('origin')

Exception Type: NameError at /dcim/rear-ports/3950/trace/ Exception Value: name 'obj' is not defined

Additional Info

• Adding a device with a interface on the other end of panel 2 and tracing produces same result
• Tracing from added device works correctly however