nix-instantiate output toys with neomake output parsing

[teto]

Issue description

I was wondering why neomake's nix maker stopped working after updating to nix-shell 2.0. It seems like it can't parse the output of nix-instantiate anymore because of the CSI color characters according to neomake.log

06:21:42 [D      ] [1.1:5:1] cwd: /home/teto/nixpkgs.
06:21:42 [D      ] [-.-:5:1] automake: started jobs: [1].
06:21:42 [D +0.07] [1.1:5:1] stderr: nix_instantiate: ['�[31;1merror:�[0m syntax error, unexpected ''='', expecting '';'', at �[1m/home/teto/nixpkgs/pkgs/top-level/lua-packages.nix�[0m:66:10', ''].
06:21:42 [D      ] [1.1:5:1] exit: nix_instantiate: 1.
06:21:42 [D      ] [1.1:5:1] nix_instantiate: processing 1 lines of output.
06:21:42 [D      ] [1.1:5:1] Creating location list.
06:21:42 [D      ] [1.1:5:1] Processing 1 entries.
06:21:42 [D      ] [1.-:5:1] File-level errors cleaned.
06:21:42 [D      ] [1.1:5:1] Skipped 1 entries without bufnr: [{'lnum': 0, 'bufnr': 0, 'col': 0, 'valid': 0, 'vcol': 0, 'nr': -1, 'type': 'W', 'maker_name': 'nix_instantiate', 'pattern': '', 'text': '�[31;1merror:�[0m syntax error, unexpected ''='', expecting '';'', at �[1m/home/teto/nixpkgs/pkgs/top-level/lua-packages.nix�[0m:66:10'}].
06:21:42 [D      ] [1.1:5:1] Handling location list: executing lwindow.

shouldn't nix-instantiate doesn't try to print colors when not on a tty ?
Is there a flag to disable the color (couldn't find in man).

Steps to reproduce

Install neomake on vim/neovim (https://github.com/neomake/neomake), then add an error into a nix file and save it. Neomake doesn't show the error as it did.

[teto]

Thanks for fixing this. I noticed the same behavior when doing nix search toto | less with nix2_.0pre5968_ac6c0b773 (aka characters appear in less output, for now I aliased less=less -R)