feature request: opam switch import --deps-only

[hannesm]

Hello,

I've a feature request -- similar to opam install --deps-only, can we have a opam switch import --deps-only -- which only imports the dependencies, but not the root set, of a switch export file? I tried myself at such a patch, but lacked API knowledge to figure out the path.

Best,

Hannes

[dbuenzli]

These things should likely be looked together with #2211. How to derive new switches from existing ones is a weak point at the moment.