Some joker thought he had caught me when I complained the Rust source code was doing early exits on exceptional cases in code I had to hack on to get it NOT to recognize my system was NixOS. (I have an actual, fully functioning /usr/local on a NixOS platform. This is difficult to do NOT because NixOS is a Post-Unix operating system, but because NixOS developers are authoritarian lunatics who do things like put in patches and mangle gcc to try to stop you from setting up a working /usr/local.)