haskellPackages.gi-gtk doesn't seem to build documentation for the generated bindings

[typetetris]

Issue description

haskellPackages.gi-gtk doesn't seem to build documentation for the generated bindings.

Neither the store path of the package contains any .html files nor does ghcWithHoogle allow
hoogle to pick up some function from the generated bindings.

Steps to reproduce

nix-shell -p 'haskellPackages.ghcWithHoogle(p: [p.gi-gtk])' and in the nix-shell start hoogle
via hoogle server and search for example for gi-gtk. Nothing shows up.

Technical details

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

system: "x86_64-linux", multi-user?: yes, version: nix-env (Nix) 2.0.4, channels(root): "nixos-unstable-18.09pre145679.dae9cf6106d, nixos-18.03.132865.411cc559c05", channels(erwonix): "", channels(typetetris): "", nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs

I tried with nixos-unstable.

[stale]

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