title: building custom packages in a user's home directory
body: <p>I've noticed that any attempt to build custom packages in a user's home directory fails, due to the home directory permissions:</p>
  
  
  
  <pre><code>drwx------
  </code></pre>
  
  <p>coupled with the fact that <code>nix-rebuild switch</code> uses the <code>nixbld{n}</code> user.</p>
  
  <p>Is there any way of getting around that? Can custom packages (user config files, for example) be built in a user's home directory, or is does this go against the underlying principles of NixOS?</p>