… failing

Security audit has been red on every main commit since fc325f4, on all three
pip scan-packages legs, with a single un-baselined CRITICAL:

  C2 polling/beaconing loop detected
  huggingface-hub  huggingface_hub/utils/_http.py
  L461:     while True: sha256:b087631...

No repo commit caused it. fc325f4 changed workflows and one test file, nothing
that resolves a dependency. What moved is upstream: the resolved huggingface-hub
came off the 0.x line, and 1.26.1, 1.27.0 and 1.28.0 all carry this loop while
0.36.2 does not. Reproduced locally against each of those versions, and the sha256
matches CI's byte for byte.

The code is `http_backoff`: it counts nb_tries against max_retries, sleeps with
exponential backoff between attempts, and raises once the budget is spent. A
bounded retry, not a beacon. RE_C2_POLLING is `while True .* sleep .* requests\.`
under re.DOTALL, which cannot tell those apart, so the file is allowlisted rather
than the check weakened -- consistent with the 51 CRITICALs already reviewed this
way, four of them this same check in this same package.

Added with the scanner's own --write-baseline so the evidence_hash is computed by
the code that will match it, then merged as a single entry rather than by
regenerating: a full rewrite re-sorts the file and turns a one-entry review into a
731-line diff. Nothing else added or removed, asserted on both directions of the
key set.

Worth recording: this file now holds FOUR entries for this check, at L298, L461,
L462 and L461 again, one per revision of the loop huggingface-hub has shipped.
That is the mechanism working -- the key is digest-pinned, so every edit reopens
the finding for review -- but it means a hub release touching those thirty lines
turns Security audit red again. The new test says so, so the next one is read as
upstream drift rather than a break.

test_the_hf_backoff_suppression_is_narrow guards the part that actually matters
about silencing a CRITICAL in a file that already speaks HTTP: every entry stays
pinned to reviewed code, none are duplicated, and a beaconing loop appended to the
same file under the same check produces a different key rather than inheriting the
suppression. Three mutations checked red (drop the entries, strip the sha256 pin,
duplicate an entry).

Verified: scan of huggingface-hub 1.28.0 goes 1 CRITICAL to 0, exit 1 to 0.
tests/security/test_scan_packages.py 123 passed.

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