Download Ubuntu test ISOs

dl-ubuntu-test-iso is a command line tool to download daily images of
Ubuntu and its flavors from cdimage.ubuntu.com. It is highly configurable
from the command line or its configution file.

NOTE THAT RUNNING THIS SCRIPT WILL DOWNLOAD A LOT OF DATA BY DEFAULT. More
specifically, it will download every ISO by default, for a total of several
tens of gigabytes of data.

Download latest Ubuntu Desktop amd64 image:

`dl-ubuntu-test-iso --flavor=ubuntu --variant=desktop --arch=amd64 --release=groovy --build=pending --isoroot=/storage/iso

Download latest Ubuntu Mate amd64 image:

dl-ubuntu-test-iso --flavor=ubuntu-mate --variant=desktop --arch=amd64 --release=groovy --build=pending --isoroot=/storage/iso

Download everything:

dl-ubuntu-test-iso --isoroot=/storage/iso`

Once install the documentation is available at /snap/dl-ubuntu-test-iso/current/usr/share/doc/dl-ubuntu-test-iso/dl-ubuntu-test-iso.README

Happy testing everyone!