D8270: run-tests: restrict Rust thread pool to 3 threads during tests

[pulkit (Pulkit Goyal)]

pulkit added inline comments.

INLINE COMMENTS

> run-tests.py:2998
> +        # multi-threading bugs while keeping the thrashing reasonable.
> +        os.environ.setdefault("RAYON_NUM_THREADS", "3")
> +

Should we also take value of `-j` into account too? If `-j 1` is used, then we should not do multi-threading here.

REPOSITORY
  rHG Mercurial

CHANGES SINCE LAST ACTION
  https://phab.mercurial-scm.org/D8270/new/

REVISION DETAIL
  https://phab.mercurial-scm.org/D8270

To: Alphare, #hg-reviewers
Cc: pulkit, mercurial-devel