Comment 19 for bug 1824236

Thanks Eric for reviewing the debdiffs.

To answer your question I need to take a step back and explain how the supermin appliance
is created and used, at least to the extend I've understood.
Supermin appliances are tiny appliances similar to a virtual machines.
Libguestfs tools depend on supermin to access and modify disk images.
For example, in the test case of the bug description guestfish lunches a supermin
appliance to mount the xenial disk image and operate on it.

The patch concerns the appliance and not the host system; it removes the resolved
hook from the appliance tree.
When libguestfs package is built some packages are copied from the host (along with
their dependencies) to be included in the supermin appliance.
Although systemd is not used inside the appliance it is listed into these packages
and exists in the appliance.
This is how we end up with the resolved hook in Ubuntu.
Given that systemd is not used by the appliance removing the hook should not be
an issue.
AFAIK this hook exists only in Ubuntu, so on any other distro this patch will
try to remove a non-existing file from the appliance, it will fail silently and
execution will continue without affecting the functionality of the appliance.

I tried to do what you suggest, first checking whether we run on Ubuntu and then
remove the hook.
However, this wouldn't work because the files which tell us the distro such as
/etc/lsb-release is not present in the appliance.
The appliance copies in some files from the build host and some from the host at
runtime, however it does not copy in all of them.
It is similar to the case in LP #1650740 where the /etc/fstab file was missing.