Many warnings on macos-latest and ubuntu-latest

[mgree]

During the OPAM install for 4.13.x (and other versions too), there are many warnings, both on macos-latest and ubuntu-latest.

None of these warnings are harmful causing failures, but they make finding other failures hard.

[smorimoto]

It's not a real issue with the Action, but in some sense, with opam-repository. That being said, more importantly it's not a real issue even with opam-repository. I understand that they are annoying with search, but I don't know how to actually make it go away.
@kit-ty-kate Do you have any ideas?

[kit-ty-kate]

I’m not sure where these warnings come from, they don’t appear in normal operation nor in opam-repo-ci for example.
Could you list which OPAM* environment variables setup-ocaml has?

[smorimoto]

The environment variables we are handling for the current system are:.

{
  "common": {
    "OPAMCLI": "2.0",
    "OPAMCOLOR": "always",
    "OPAMERRLOGLEN": 0,
    "OPAMJOBS": "(Number of logical CPU cores)",
    "OPAMPRECISETRACKING": 1,
    "OPAMSOLVERTIMEOUT": 1000,
    "OPAMVERBOSE": (true | false), // Depends on whether action step debugging is on
    "OPAMYES": true,
    "DUNE_CACHE": true,
    "DUNE_CACHE_TRANSPORT": "direct"
  },
  "windows-specific": {
    "OPAMROOT": "D:/.opam",
    "HOME": "process.env.USERPROFILE",
    "MSYS": "winsymlinks:native"
  }
}