Select stanza broken (when using -only-packages)

[hhugo]

Broken Behavior

I have git repo that contains multiple opam packages.
I have a library A with an optional (select stanza) dependency on a library B that is also part of the repo but marked as vendor-ed.
After installing A with opam pin (B is not installed), I see B in the requires section of the A's lib/A/dune-package.
Trying to install a third package C result in the following error.

# File ".opam/....../lib/A/dune-package", line .., characters ...:
# 87 |   B)
#        ^^^^^^^^^^^^^^^^^^
# Error: Library "B" not found.

If I remove B from the repo and reinstall A. Everything works fine

Specifications

• Version of dune 2.9
• Version of ocaml 4.12
• Version of opam 2.1.0

[rgrinberg]

Is this a bug in 3.1.x as well? If so, could you add a reproduction test case to the repo?

[hhugo]

I confirm that this affects dune.3.1.x as well

[hhugo]

There was one missing aspect in my initial report. The issue only triggers when the optional library in marked as vendor-ed.

[hhugo]

could be related to #4962

[rgrinberg]

Replaced by #7197