hooks failed to run because it was already open (on NixOS)

[MathisWellmann]

I tried using some plugins (docker, docker-compose, etc) in my pipeline as such:

steps:
  - label: ":docker: :rust: build"
    command: RUSTFLAGS="-D warnings" cargo build
    plugins:
      - docker-compose#v3.0.3:
          run: node
    agents:
      queue: nixos

Which is executed by the agent on a nixos host, which successfully runs all my other pipelines, but this setup fails to run with the following message:

$ /var/buildkite/plugins/github-com-buildkite-plugins-docker-compose-buildkite-plugin-v3-0-3/hooks/pre-checkout
🚨 Error: The plugin docker-compose pre-checkout hook failed to run because it was already open. We couldn't find out what process had the hook open
🚨 Error: error running "/tmp/buildkite-agent-bootstrap-hook-runner-1100140013": fork/exec /tmp/buildkite-agent-bootstrap-hook-runner-1100140013: no such file or directory

@tomowatt gave insight into why this is happening here: buildkite-plugins/docker-compose-buildkite-plugin#434 (comment)

TLDR: The /bin/bash executable exists at a different path in NixOS as it departs from the FHS (File hierarchy standard) to ensure reproducibility. The plugin scripts rely on bash being there and it thus fails.

The only real issue here is that the above error message is cryptic and could be improved.
Fixing the path in the nix package is possible to support existing scripts / plugins.