`project_root`/submodules build-failure in the dev branch of `ocaml-lsp-server`

[ELLIOTTCABLE]

Pinning all your various branches manually and resolving dependencies, we got pretty far — but unfortunately, the very last stage (ocaml-lsp-server) fails with an obscure build-error, pretty much no matter what we do:

#=== ERROR while compiling ocaml-lsp-server.20230116.voodoos-git ==============#
# context     2.1.2 | linux/x86_64 | ahrefs-setup.git ocaml-base-compiler.4.14.0 | file:///home/me/code/monorepo.worktrees/aa/web-split/backend/opam
# path        ~/code/monorepo.worktrees/aa/web-split/_opam/.opam-switch/build/ocaml-lsp-server.20230116.voodoos-git
# command     ~/.system/Dotfiles/opam/opam-init/hooks/sandbox.sh build dune build -j 47 ocaml-lsp-server.install --release
# exit-code   1
# env-file    ~/.system/Dotfiles/opam/log/ocaml-lsp-server-2945551-574694.env
# output-file ~/.system/Dotfiles/opam/log/ocaml-lsp-server-2945551-574694.out
### output ###
# File "ocaml-lsp-server/vendor/dune", line 2, characters 13-70:
# 2 |  (copy_files %{project_root}/submodules/dune/src/ocamlc_loc/*.{ml,mli})
#                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
# Error: Cannot find directory: submodules/dune/src/ocamlc_loc

<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
┌─ The following actions failed
│ λ build ocaml-lsp-server 20230116.voodoos-git
└─ 

[voodoos]

My guess is that you should pin at least ocaml-lspwith--with-version=dev`. For an easier setup you can use the switch export in https://github.com/voodoos/merlin-occurrences-switch