KeyError when toggling interface connection status via web UI

[jeremystretch]

Environment

• Python version: 3.5.6
• NetBox version: 2.4.1

Steps to Reproduce

1. Create a connection between any two interfaces.
2. Click the "mark planned" button on one of the interfaces to toggle the connection status.

Expected Behavior

The connection status should be updated to "planned" and the table row should change color to blue.

Observed Behavior

The connection status does get updated in the database, however the API response fails, yielding a KeyError:

...
  File "/home/jstretch/netbox/netbox/utilities/api.py", line 74, in to_representation
    return {'value': obj, 'label': self._choices[obj]}
KeyError: 'False'