For example, if one of the modules dkms would build is not newer than what is
already found in the Debian kernel, dkms won't build it and our previous
sanity check would abort the build:

 /etc/kernel/header_postinst.d/dkms:
 Error! Module version 5.2.16_Debian for vboxvideo.ko
 is not newer than what is already found in kernel 4.17.0-1-amd64 (5.2.16_Debian).