$NIX_GHC_DOCDIR points to non-existent directory

[ParetoOptimalDev]

Describe the bug

related to #150968 and found while writing a feature request for haskell language server support for local nix documentation in haskell/haskell-language-server#3475

Steps To Reproduce

Steps to reproduce the behavior:

1. git clone https://github.com/ParetoOptimalDev/apecs-shmup-example.git
2. cd apecs-shmup-example
3. nix develop -c bash -c "ls $NIX_GHC_DOCDIR"

Get:

ls: cannot access '/nix/store/0g44g3x3qc5rpmr8n1m4bldl0fwlc4z0-ghc-9.2.4-with-packages/share/doc/ghc/html': No such file or directory

Expected behavior

It returns the correct directory which seems to be different for each package and not nested anywhere, e.g. apecs:

/nix/store/pmyb1ayz7vxlmim1bd12sjpss3s7pddy-apecs-0.9.4-doc/share/doc/apecs-0.9.4/html/src/Apecs.Util.html

Screenshots

If applicable, add screenshots to help explain your problem.

Additional context

The reason for wanting this is to simplify implementing hover links in haskell language server being able to link to local nix generated hackage docs and source as in feature request haskell/haskell-language-server#3475

Notify maintainers

@maralorn @sternenseemann @KAction @cdepillabout @expipiplus1

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

[sternenseemann]

Duplicate of #150666, fixed in #210762.