Comment 12 for bug 1728742

The bcache-export-cached udev script did not skip cache devices and would emit a cache device dev.uuid; I'm testing a change to ignore those and that appears to get things working on my single cache, multiple backing device test-case.

I've also some changes on the curtin side which will emit the udev dname rule based on the backing device uuid, and also write out the dname value into the backing device 'label' so there will be those symlinks as well.