Fixes #1847: Fix RecursionError when VC master device is unnamed

netbox/dcim/models.py

@@ -1044,7 +1044,7 @@ class Device(CreatedUpdatedModel, CustomFieldModel):
     def display_name(self):
         if self.name:
             return self.name
-        elif hasattr(self, 'vc_membership'):
+        elif hasattr(self, 'vc_membership') and self.vc_membership.virtual_chassis.master.name:
             return "{}:{}".format(self.vc_membership.virtual_chassis.master, self.vc_membership.position)
         elif hasattr(self, 'device_type'):
             return "{}".format(self.device_type)