title: Is it possible to update rustup once and share the downloads with other systems?
body: <p>I'd like to save bandwidth by invoking <code>rustup update</code> and updating the installed toolchains, then sharing the updated toolchains to another system without having to download the toolchains again. Is this possible?</p>
  
  <p>Looking at the .rustup directory, it seems copying the toolchains directory might work but I'm afraid of causing a mismatch between rustup's metadata on what it has installed and what's actually installed, or other such problems. Unless someone says it's OK to do this, I don't think this is an option.</p>