nixos-rebuild build-vm don't boot because of PR 236656

[symphorien]

Describe the bug

VMs generated by nixos-rebuild build vm don't boot, they timeout waiting for a partition labeled nixos.

Steps To Reproduce

Steps to reproduce the behavior:
1.
create a file vm-minimal.nix:

{ config, pkgs, lib, ... }: {
  config = {
    console = {
      font = "Lat2-Terminus16";
      keyMap = "fr";
    };
    users.users.alice = {
      isNormalUser = true;
      initialPassword = "alice";
    };
    users.mutableUsers = false;
    documentation.enable = false;
  };
}

2. build a vm from this configuration

nixos-rebuild build-vm -I nixos-config=temp/vm-minimal.nix -I nixpkgs=. && result/bin/run-nixos-vm

4. the vm does not boot

waiting for device /dev/disk/by-label/nixos to appear......
timeout waiting for device /dev/disk/by-label/nixos trying to mount anyway
[   22.812144] /dev/disk/by-label/nixos: Can't open blockdev

Expected behavior

the vm boots

Screenshots

Additional context

I bisected this issue down to #236656

Notify maintainers

Metadata

Please run nix-shell -p nix-info --run "nix-info -m" and paste the result.

[user@system:~]$ nix-shell -p nix-info --run "nix-info -m"
output here

---

Add a 👍 reaction to issues you find important.

[symphorien]

Actually I needed to remove nixos.qcow2 in the current working directory. Old images break the new code.