upgrade is not suitable for neon because we carry out transitions all the
time. the overlay prevents running upgrade altogether, instead opting to
educate the user.
the upgrade will run all the same if -y is passed so as to prevent things
falling apart for scripts and the like (which are all expected to pass -y
or they are doing it wrong one would think)
since the overlay is is in sbin this always overrides the regular apts
(given a suitable PATH setup, which is the case by default). calling
apt by absolute path in usr/bin/ also bypasses the overlay (again,
something a well-behaved script should probably do)