there is a request for not installing the PReP partition on PPC system
that don't really require it in bug 1303219 . I've spend some time
working on it and I think I have the solution, see  for details.
Because the testing requires a bare-metal Power machine I'm now thinking
how to allow testing it with the community in the least intrusive way.
Right now my plan is to have the anaconda PR merged and use an
updates.img for the corresponding blivet change. This way anaconda
itself should work as before and only when used with the updates.img it
should change the behaviour. What do you think?