Nix CLI prints control chars into stderr which cause inconsistent result

[luochen1990]

Describe the bug

Run nix command multiple times, and you can get different output, even for read-only commands.

See also: BurntSushi/ripgrep#2899

Steps To Reproduce

1. Run nix registry list | rg nixpkgs multiple times (10 might be enough)
2. See the Inconsistent output result

$ nix registry list | rg nixpkgs
system flake:nixpkgs path:/nix/store/asmpdfb2aixsjl95a557c269ybzybjm3-source
global flake:nixpkgs github:NixOS/nixpkgs/nixpkgs-unstable
$ nix registry list | rg nixpkgs


$ nix registry list | rg nixpkgs


$ nix registry list | rg nixpkgs


$ nix registry list | rg nixpkgs

global flake:nixpkgs github:NixOS/nixpkgs/nixpkgs-unstable

Expected behavior

The output shoud be the same with the same command

nix-env --version output

Additional context

Just use nix repl and without rg can still reproduce this issue (when something is slow to evaluate).

Priorities

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