Comment 1 for bug 1979036

Another testcase is failed.

The test com.canonical.certification::ethernet/detect failed with the error list blow:
-------------[ Detect if at least one ethernet device is detected ]-------------
ID: com.canonical.certification::ethernet/detect
Category: com.canonical.plainbox::ethernet
... 8< -------------------------------------------------------------------------
Traceback (most recent call last):
  File "/tmp/nest-m_b8ini3.9a94080dfa9d0226560c697ac550c8dc840cf7385cc17eb075a488d5c7c11d21/network_device_info.py", line 393, in <module>
    udev = UdevDevices(args.category)
  File "/tmp/nest-m_b8ini3.9a94080dfa9d0226560c697ac550c8dc840cf7385cc17eb075a488d5c7c11d21/network_device_info.py", line 338, in __init__
    self._collect_devices()
  File "/tmp/nest-m_b8ini3.9a94080dfa9d0226560c697ac550c8dc840cf7385cc17eb075a488d5c7c11d21/network_device_info.py", line 346, in _collect_devices
    output = check_output(cmd).decode(sys.stdout.encoding)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xc0 in position 38854: invalid start byte