[pkg management] can't install cohttp 6.0.0~beta2 with developer preview

[maxRN]

Expected Behavior

dune pkg lock adds cohttp version 6.0.0~beta2 https://ocaml.org/p/cohttp/6.0.0~beta2

Actual Behavior

Fails with:

Error: Unable to solve dependencies for the following lock directories:
Lock directory dune.lock:
Can't find all required versions.
Selected: pkg_repro.dev
- cohttp -> (problem)
    pkg_repro dev requires = 6.0.0~beta2
    Rejected candidates:
      cohttp.5.3.1: Incompatible with restriction: = 6.0.0~beta2
      cohttp.5.3.0: Incompatible with restriction: = 6.0.0~beta2
      cohttp.5.2.0: Incompatible with restriction: = 6.0.0~beta2
      cohttp.5.1.0: Incompatible with restriction: = 6.0.0~beta2
      cohttp.5.0.0: Incompatible with restriction: = 6.0.0~beta2
      ...

Reproduction

Link to reproduction repository. Manual steps:

1. Create new project.
2. Add (cohttp (= 6.0.0~beta2)) to dependencies.
3. Run dune pkg lock

Specifications

• Version of dune (output of dune --version):

  "Dune Developer Preview: build 2024-11-20T02:20:21Z, git revision
  5ac095c7c0c13ba5bf2de1becbe512d893c4e72b"

• Version of ocaml (output of ocamlc --version): None
• Operating system (distribution and version): MacOS Sequoia 15.1

Additional information

Output of dune pkg lock --verbose:

Shared cache: enabled
Shared cache location: /Users/maxrn/.cache/dune/db
Workspace root: /Users/maxrn/code/dune-pkg-repro
Auto-detected concurrency: 10
Running[3]: (cd /Users/maxrn/.cache/dune/git-repo && /etc/profiles/per-user/maxrn/bin/git ls-remote https://github.com/ocaml-dune/opam-overlays.git) > /var/folders/gr/fh9_6fn53l7f4sczxc4xphv40000gn/T/dune_eb9628_output
Running[4]: (cd /Users/maxrn/.cache/dune/git-repo && /etc/profiles/per-user/maxrn/bin/git ls-remote https://github.com/ocaml/opam-repository.git) > /var/folders/gr/fh9_6fn53l7f4sczxc4xphv40000gn/T/dune_abe6be_output
Error: Unable to solve dependencies for the following lock directories:
Lock directory dune.lock:
Can't find all required versions.
Selected: pkg_repro.dev
- cohttp -> (problem)
    pkg_repro dev requires = 6.0.0~beta2
    Rejected candidates:
      cohttp.5.3.1: Incompatible with restriction: = 6.0.0~beta2
      cohttp.5.3.0: Incompatible with restriction: = 6.0.0~beta2
      cohttp.5.2.0: Incompatible with restriction: = 6.0.0~beta2
      cohttp.5.1.0: Incompatible with restriction: = 6.0.0~beta2
      cohttp.5.0.0: Incompatible with restriction: = 6.0.0~beta2
      ...

[maiste]

Absolutely not sure about it but may be related to #11136.

[rgrinberg]

Yup, it's a duplicate.