if (auto it = std::ranges::find_if(
            externalBuilders.get().begin(),
            externalBuilders.get().end(),
            [&](const auto & handler) {
                return std::ranges::find(handler.systems, drv.platform) != handler.systems.end();
            });
        it != externalBuilders.get().end())
        return &*it;
    return nullptr;

Sergei Zimmerman (xokdvium): RE https://github.com/NixOS/nix/pull/14209#discussion_r2422146488

I can make the change to include the s3 params in the cacheKey

nix, or nixpkgs, does not really have a concept of multiple extant versions of a package. i see this worked around in cases of overwhelming importance with e.g. python312, python313 etc.

but in general if you need an older version of package XYZ you are dealing with a git history search and pinning to a commit

there is no fundamental reason why nixpkgs HEAD could not contain the logic for multiple versions of package XYZ

so - to start from the beginning - is there something in nix itself that keeps me from e.g. writing opentofu-1.6.3 or opentofu==1.6.3 or whatever as the package i want to install?

background: i want to introduce nix devshells in a company where this kind of situation happens all the time (i.e. some project has to be checked out from github and worked on using a list of software versions that is both brittle and not recent)