make-edge-iso fails on Bionic images: cannot reload udev rules: exit status 2

[Paride Legovini]

The make-edge-iso.sh script doesn't work with the ubuntu-bionic-live-server-amd64 images. The script works fine with Focal images on the same machine. This is always reproducible. Full log attached, however the failing part is:

+ /usr/lib/snapd/snap-preseed /tmp/tmp.oPStTDsIYP/tree
starting to preseed root: /tmp/tmp.oPStTDsIYP/tree
using snapd binary: /tmp/snapd-preseed/usr/lib/snapd/snapd (2.45.2)
AppArmor status: apparmor is enabled and all features are available
2021/02/02 11:59:12.043806 main.go:57: running for preseeding
2021/02/02 11:59:12.067975 daemon.go:343: started snapd/2.45.2 (series 16; classic) ubuntu/18.04 (amd64) linux/4.15.0-135-generic.
2021/02/02 11:59:12.154685 daemon.go:436: adjusting startup timeout by 30s (pessimistic estimate of 30s plus 5s per snap)
2021/02/02 11:59:12.259414 helpers.go:105: error trying to compare the snap system key: system-key missing on disk
2021/02/02 11:59:13.876049 taskrunner.go:271: [change 1 "Setup snap \"snapd\" (8542) security profiles" task] failed: cannot reload udev rules: exit status 2
udev output:
cannot preseed: cannot reload udev rules: exit status 2
udev output:

unmounting: /tmp/snapd-preseed
error: error running snapd in preseed mode: exit status 1

[Michael Hudson-Doyle (mwhudson)]

Ah this will be because bionic ISOs are not preseeded already I guess? I wonder how to detect that.