unpacking 'https://channels.nixos.org/nixpkgs-unstable/nixexprs.tar.zst' into the Git cache...
Running phase: initPhase
@nix { "action": "setPhase", "phase": "initPhase" }
Running phase: userSetupPhase
@nix { "action": "setPhase", "phase": "userSetupPhase" }
Running phase: effectPhase
@nix { "action": "setPhase", "phase": "effectPhase" }
To https://git.luj.fr/luj/snowfield.git
 ! [rejected]        HEAD -> deploy (non-fast-forward)
error: failed to push some refs to 'https://git.luj.fr/luj/snowfield.git'
hint: Updates were rejected because a pushed branch tip is behind its remote
hint: counterpart. If you want to integrate the remote changes, use 'git pull'
hint: before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.
error: nix failed with exit code 1