Interface Bulk Import Exception when adding interfaces to virtual machines

[dealer-san]

Environment

• Python version: 3.6.8
• NetBox version: 2.7.3

Steps to Reproduce

1. Select "Devices" -> Interfaces -> Import
2. Enter CSV interface data using virtual_machine column type (e.g., virtual_machine,name,type)
3. Submit

Expected Behavior

Either interfaces are imported successfully or data validation errors are reported.

Observed Behavior

Submission results in the following Python exception.

Example input data:

virtual_machine,name,type
hostname,eth0,Virtual

The import seems to work without problems when importing for devices. Was able to reproduce issue in clean installs of both v2.7.2 and v2.7.3.