[Nix-dev] Best practices for replacing channels with my own package set?

[Jeffrey David Johnson]

I'd like all the nix tools to reference my package repository, which is
called mypkgs and re-exports nixpkgs with some custom ones added. I
base it on the latest nixos-unstable revision so there should be
binaries available.

Currently I set NIX_PATH using `environment.interactiveShellInit`. That
seems to work for everything except nix-env, so I alias it to `nix-env
-f /path/to/mypkgs`. But I'm a little worried there might be parts of
the system still depending on ~/.nix-defexpr, /etc/nixos etc. Anything
else I should be doing?
Jeff