I have a Nix flake with several inputs whose URLs are remote git repositories. I want to update one input in flake.lock, but not the others; in particular, I want to avoid repinning nixpkgs.
When I run nix flake update, all inputs are updated. This is probably desirable for correctness. However, I can subsequently roll back part of the changes to flake.lock, performing minor surgery, so that only one input is updated.
Is there a blessed or safe way to update only one input? I would accept a way to update a given input and all of its transitive dependencies, if that is the only safe way.