Verification-done for xenial, using shim-signed 1.32~17.04.1:
Interactive, non-interactive (old dkms update) and non-interactive (new pulled update) react as expected. I have tested that the interactive installs always prompt the user; but also that any unattended-upgrade run correctly fails if trying to install a new DKMS module that was not previously present (as it can't prompt the user), but complete successfully if upgrading an already-installed DKMS module.
Verification-done for xenial, using shim-signed 1.32~17.04.1:
Interactive, non-interactive (old dkms update) and non-interactive (new pulled update) react as expected. I have tested that the interactive installs always prompt the user; but also that any unattended-upgrade run correctly fails if trying to install a new DKMS module that was not previously present (as it can't prompt the user), but complete successfully if upgrading an already-installed DKMS module.