Preserve option for up

[jariji]

When I do up Foo@1.2.3 it sometimes doesn't do anything because it's preserving something else. I would like instead if it preserved as much as possible while still doing the upgrade I asked for. Would that be possible?

[serenity4]

You can do up --preserve=direct Foo@1.2.3 manually, but that means you may also change versions of dependencies that didn't need to be changed, and the update is no longer minimal.

Preserving everything else by default causes some confusion, as e.g. reported in #4087.