$ sudo ubuntu-device-flash core --channel edge --oem odroidc_0.3_all.snap --device-part device-odroidc_0.3.tar.xz --developer-mode -o odroidc-rolling.img 15.04
Determining oem configuration
2015/07/22 18:22:09 Signature check failed, but installing anyway as requested
Fetching information from server...
Downloading and setting up...
45.43 MB / 45.43 MB [====================================] 100.00 % 842.43 KB/s 
Installing odroidc_0.3_all.snap
2015/07/22 18:23:20 Signature check failed, but installing anyway as requested
Enabling developer mode...
New image complete
Summary:
 Output: odroidc-rolling.img
 Architecture: armhf
 Channel: edge
 Version: 125


sudo ubuntu-device-flash core --channel edge --oem odroidc_0.3_all.snap --device-part device-odroidc_0.3.tar.xz --developer-mode -o odroidc-rolling.img rolling
Determining oem configuration
2015/07/22 18:28:05 Signature check failed, but installing anyway as requested
Fetching information from server...
Downloading and setting up...
Installing odroidc_0.3_all.snap
2015/07/22 18:28:48 Signature check failed, but installing anyway as requested
failed to find user uid/gid
2015/07/22 18:28:48 Warning: failed to remove /tmp/diskimage551242846/system/oem/odroidc/0.3: %!s(<nil>)
2015-07-22 16:28:48 ERROR snappy logger.go:199 odroidc_0.3_all.snap failed to install: unpack odroidc_0.3_all.snap to /tmp/diskimage551242846/system/oem/odroidc/0.3 failed with exit status 1
odroidc_0.3_all.snap failed to install: unpack odroidc_0.3_all.snap to /tmp/diskimage551242846/system/oem/odroidc/0.3 failed with exit status 1