What to do with OOD targets, that has not changed their output?

How to prevent building of targets, who depend on the OOD target, that
produced the same output? If the target is already decided to be OOD,
then the whole tree becomes OOD too. It is clear, simple, reliable and
honest way of do-ing things.

Building of the lower level OOD target first is unfair and dishonest
thing to do, because probably top level target, being the OOD, won't be
dependant on lower level target anymore at all. Actually goredo does
this as a shameful hack and only for always-targets, still existing in
the wild. The whole redo-always idea is considered harmful.

If you wish to run something and decide if it must OOD the toplevel
targets, then just run redo to forcefully rebuild it and then run the
ordinary top level targets.