Experimentation: 0.5.24 Issue

[chiroptical]

See https://github.com/ceedubs/unison-nix/issues/97

[chiroptical]

I've narrowed down the issue to the post fixup phase. Commenting this allows me to add ucm via home-manager. You can test this yourself by changing your inputs to,

inputs = {
    unison-lang = {
        type = "github";
        owner = "chiroptical";
        repo = "unison-nix";
        ref = "chiroptical/issue-97";
    };
};