To be a good professional engineer, always start to study late
for exams, because it teaches,you how to manage time and
tackle emergencies. (Bill Gates)

A problem that sometimes arises. The solution is simple, but it is hard to find, so I though I will write it here, such that other Googlers will find it.

You can simply do this by adding a policy-rc.d-script. That is, create a script /usr/sbin/policy-rc.d returning 101, before installing anything.

When using packages, the above Link sais one must use the alternatives-System, which sounds plausible.

Well, I have learned that today. It is always interesting to learn something new.