> Pkg.add can now be told to prefer to add already installed versions of packages (those that already have been downloadedd onto your machine) > set the env va

> Pkg.add can now be told to prefer to add already installed versions of packages (those that already have been downloadedd onto your machine) > set the env var `JULIA_PKG_PRESERVE_TIERED_INSTALLED` to true. How is this different from setting `Pkg.offline(true)` and then doing the `add`? I don't know the intricacies of how it works, but that's what I've been doing when I just need to try something out in a temp environment.