At some point in the past, virt-builder and other tools had proper networking
with-in the appliance. This still works by luck in SLE15, but it broke in
Tumbleweed.

The reason is the transformation of appliance/packagelist.in into
/usr/lib64/guestfs/supermin.d/packages. During build the packagelist is passed
to supermin, which writes the packages file. In case a package is unavailable
during build, it will be missing from the packages file. Also 'systemd' is
transformed into 'systemd-mini' (which is not really an issue because other
packages require 'systemd').

In case of networking: if the host does not have 'dhcp-client' installed, the
network will not start inside the appliance. Once dhcp-client gets installed,
it will be put into the appliance. But the dhcp-client scripts expect a
functional /sbin/netconfig, which is provided by sysconfig-netconfig. That
package is listed in packagelist.in, but will not be written to packages
because it is not in BuildRequires.

I think most packages from packagelist.in are "lost" during build because they
are not in BuildRequires, or because nothing requires them. It feels wrong to
put each and every binary which is potentially called by guestfsd into
BuildRequires.

Instead the "packages" file should be overwritten manually with the list of
packages which may be used, if it is installed on the host.