It's currently not possible to use an image in the Bitbucket pipleline, that doesn't have `/usr/bin/mkfifo` or `/bin/echo`, resulting in the error:

```

/bin/sh: /usr/bin/mkfifo: No such file or directory

/bin/sh: /bin/echo: No such file or directory

```

An example for this is the [Nix-Image](https://hub.docker.com/r/nixos/nix), or basically any image coming out of [Nixery](https://nixery.dev/)

If these commands are really needed for the pipline, I suggest to at least check if they're somewhere in the PATH first, before using the hardcoded location. But best would be if they're not needed or somehow passed into the container, so the container doesn't have to have a specific form.

This would help us a lot. And the ability to use nixery would be a dream!

Thanks for investigating this!