Comment 5 for bug 1347329

> This is a bug, but i'm not sure if we want our defaut to be larger as it will take up more excess space on other isos

The comment in /etc/testdriverc says

    # Note that this will be a sparse, qcow2 file, so it should not actually
    # take that much space on the filesystem.

so it shouldn't be a problem.

For reference, the empty default 8 GiB image (which is empty because the Ubuntu disco desktop installer refuses to proceed due to not enough disk space) occupies only 196K on disk.