Extract from the log:

I    0.002s TimeoutThread-1-for-MainThread  [host]> /b/c/b/Android_Release__Nexus_6_/src/third_party/catapult/devil/bin/deps/linux2/x86_64/bin/adb devices
E    0.005s Main  Unable to provision local devices.
Traceback (most recent call last):
  File "/b/c/b/Android_Release__Nexus_6_/src/build/android/provision_devices.py", line 554, in main
    return ProvisionDevices(args)
  File "/b/c/b/Android_Release__Nexus_6_/src/build/android/provision_devices.py", line 74, in ProvisionDevices
    raise device_errors.DeviceUnreachableError(args.device)
DeviceUnreachableError: None

Can someone from infra take a look?