$ sudo ubuntu-device-flash core --output snappy-i386.img --device generic_i386 --size 4 --channel edge
Determining oem configuration
Fetching information from server...
Downloading and setting up...
unable to update grub: Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
ERROR: cannot determine partition label for rootfs /dev/mapper/loop0p3