Comment 1 for bug 1537553

Similarly, the script at the address no longer works, due to /userdata no longer containing a system.img with the whole root partition. The only system.img there is is /var/lib/lxc/android/system.img but that only contains the device-dependant Android files, rather than whole root fs.

https://github.com/plasma-mobile/plasma-phone-dev-setup/blob/master/usr/bin/resize-root-partition