Using
cros flash --no-stateful-update --debug --disable-rootfs-verification 100.107.3.154 xbuddy://remote/veyron_minnie/latest-dev/test

ends up with a python error stack in rc/platform/dev/xbuddy.py:
  File "/mnt/host/source/src/platform/dev/xbuddy.py", line 371, in _LS
    ['ls', '-d', '--', path]).output.splitlines()
AttributeError: 'NoneType' object has no attribute 'splitlines'

However, it seems we were able to locate the right gsutil directory:
gs://chromeos-image-archive/veyron_minnie-release/R59-9390.0.0/


If I specify that image:
cros flash --no-stateful-update --debug --disable-rootfs-verification 100.107.3.154 xbuddy://remote/veyron_minnie
We go further:
09:42:46: INFO: [22/Mar/2017:09:42:46] XBUDDY Path is remote/veyron_minnie/R59-9390.0.0/test, location suffix is -release
09:42:46: INFO: [22/Mar/2017:09:42:46] XBUDDY Get artifact 'test' with board veyron_minnie and version R59-9390.0.0'. Locally? False
09:42:46: INFO: RunCommand: /mnt/host/source/.cache/common/gsutil_4.19.tar.gz/gsutil/gsutil -o 'Boto:num_retries=10' ls -- gs://chromeos-image-archive/veyron_minnie/R59-9390.0.0
09:42:47: INFO: RunCommand: /mnt/host/source/.cache/common/gsutil_4.19.tar.gz/gsutil/gsutil -o 'Boto:num_retries=10' ls -- gs://chromeos-image-archive/veyron_minnie-release/R59-9390.0.0
09:42:48: INFO: [22/Mar/2017:09:42:48] XBUDDY Resolved version R59-9390.0.0 to veyron_minnie-release/R59-9390.0.0.
09:42:48: INFO: [22/Mar/2017:09:42:48] XBUDDY Returning path to payload: veyron_minnie-release/R59-9390.0.0/chromiumos_test_image.bin
09:42:48: INFO: [22/Mar/2017:09:42:48] XBUDDY Path is remote/veyron_minnie/R59-9390.0.0/test, location suffix is -release
09:42:48: INFO: Using image veyron_minnie-release/R59-9390.0.0/chromiumos_test_image.bin