Comment 2 for bug 1861520

Since this change only affects ubuntu-image based builds (no other code-path altered), the regression potential is really low. So all the classic images built fine, so no regression here. As for the actual bugfix, I have ran a proposed-enabled bionic core image build on cdimage - all images besides armhf+raspi3 and arm64+raspi3 built successfully. Those that failed, failed as expected - checking the build logs, the right pi model assertion was used. Failure was because of a missing gadget in the required channel, but that is to be expected (still no valid gadget there).