Booting daily-live/current wily-desktop-amd64.iso from Grub2 and updating it using zsync.

Yesterday I downloaded Ubuntu 15.10 Wily Werewolf Live ISO

wget -c http://cdimage.ubuntu.com/daily-live/current/wily-desktop-amd64.iso

 and used it booting from Grub2 menu entry as follows:

sudo gedit /etc/grub.d/40_custom

and added the following lines:

menuentry "Wily Desktop iso" {
        set isofile="/home/user/wily-desktop-amd64.iso"
        loopback loop (hd0,X)$isofile
        linux (loop)/casper/vmlinuz.efi boot=casper iso-scan/filename=$isofile noprompt noeject
        initrd (loop)/casper/initrd.lz
}

then I updated grub to add the menuentry:

sudo update-grub

I could boot from the ISO and found that Wily has Linux Kernel 4.2 which has Blue tooth driver for my Laptop and it worked well.

Today I decided to keep the ISO updated and installed zsync and used it to update.

sudo apt-get install zsync -y
zsync http://cdimage.ubuntu.com/daily-live/current/wily-desktop-amd64.iso.zsync
#################### 100.0% 108.2 kBps DONE   

reading seed file wily-desktop-amd64.iso: **************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************Read wily-desktop-amd64.iso. Target 100.0% complete.    
verifying download...checksum matches OK
used 1257062400 local, fetched 0

Since it is less than 24 hours it says " fetched 0"

If you want to use the method please note that the ISO is on /home folder of the user. Put your username replacing user and X in (hd0,X) as your partition no X.