Nix 2.21.x -> 2.22.x download buffer is full on CentOS 7

[MatthewCroughan]

Describe the bug

When using CentOS 7, I ran into an issue with nix versions 2.21.x through to 2.22.x, where builtin fetchers such as those
triggered when running nix build nixpkgs#hello fill up a buffer and fail to fetch.

Downgrading to Nix 2.18.1 or 2.18.2 makes this issue stop.

When running nix build nixpkgs#hello, nix will fail to download the GitHub tarball. Running with -vvv shows the following

download thread waiting for 100 ms
download buffer is full; going to sleep

Eventually, the download fails and the following error is emitted

error:
       … while fetching the input 'github:NixOS/nixpkgs/nixpkgs-unstable'

       error: cannot get archive member name: truncated gzip input

Steps To Reproduce

1. Get CentOS 7
2. Install Nix via the nixos.org installer
3. Get nix 2.21.x or 2.22.x
4. nix build nixpkgs#hello

Expected behavior

For Nix to successfully download and unpack the tarball.

nix-env --version output

$ nix-env --version
nix-env (Nix) 2.21.2

Additional context

I'm sorry I can't provide more helpful steps to reproduce the bug, though I'm happy to help if anyone can instruct me on what to run.

Priorities

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[MatthewCroughan]

maybe related to #10630