[lab-iot] rpi3 board fails health-check

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/lava_dispatcher/job.py", line 215, in validate
    self._validate()
  File "/usr/lib/python3/dist-packages/lava_dispatcher/job.py", line 199, in _validate
    self.pipeline.validate_actions()
  File "/usr/lib/python3/dist-packages/lava_dispatcher/action.py", line 175, in validate_actions
    action.validate()
  File "/usr/lib/python3/dist-packages/lava_dispatcher/actions/boot/u_boot.py", line 87, in validate
    super().validate()
  File "/usr/lib/python3/dist-packages/lava_dispatcher/logical.py", line 50, in validate
    super().validate()
  File "/usr/lib/python3/dist-packages/lava_dispatcher/action.py", line 491, in validate
    self.internal_pipeline.validate_actions()
  File "/usr/lib/python3/dist-packages/lava_dispatcher/action.py", line 175, in validate_actions
    action.validate()
  File "/usr/lib/python3/dist-packages/lava_dispatcher/actions/boot/u_boot.py", line 147, in validate
    super().validate()
  File "/usr/lib/python3/dist-packages/lava_dispatcher/logical.py", line 50, in validate
    super().validate()
  File "/usr/lib/python3/dist-packages/lava_dispatcher/action.py", line 491, in validate
    self.internal_pipeline.validate_actions()
  File "/usr/lib/python3/dist-packages/lava_dispatcher/action.py", line 175, in validate_actions
    action.validate()
  File "/usr/lib/python3/dist-packages/lava_dispatcher/actions/boot/__init__.py", line 796, in validate
    if self.job.device.connect_command is "":
  File "/usr/lib/python3/dist-packages/lava_dispatcher/device.py", line 67, in connect_command
    if "connect" in self["commands"]:
KeyError: 'commands'