`opam switch create --jobs=2 4.09.0+flambda` FTBFS with `debian:11-slim`

[erikmd]

In a coqorg/base build, the command opam switch create --jobs=2 4.09.0+flambda just says Please file a bug report at https://github.com/ocaml/opam-repository/issues:

…

<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
+- The following actions failed
| - build ocaml-variants 4.09.0+flambda
+- 
+- The following changes have been performed (the rest was aborted)
| - install base-bigarray base
| - install base-threads  base
| - install base-unix     base
+- 
<><> ocaml-variants.4.09.0+flambda troubleshooting ><><><><><><><><><><><><><><>
=> A failure in the middle of the build may be caused by build parallelism
      (enabled by default).
      Please file a bug report at https://github.com/ocaml/opam-repository/issues
=> You can try installing again including --jobs=1
      to force a sequential build instead.
# Run eval $(opam env --switch=4.09.0+flambda) to update the current shell environment

• Dockerfile URL
• GitLab CI pipeline URL
• Raw logs → attached job.log

Will restart the job anyway.

[erikmd]

Despite the restart, the job failed anew:

• GitLab CI pipeline URL
• GitLab CI pipeline URL

[erikmd]

On second thought: migrating to 4.09.1+flambda fixes the issue.

(I'd be curious to learn what happened exactly, but) feel free to close this issue now: it's not blocking for coqorg/base anymore.

[github-actions[bot]]

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