The 09-22 nightly chain failed all 12 lanes in seconds at the 'Bind
functional candidate' step:
ValueError: private script pin differs from chain
resolve_functional_candidate.py's >24h staleness fallback (added by
#8026, made functional by #8041's token fix) legitimately sets
manifest.testing_sha to auto-testing main HEAD, but current_chain()
still required it to equal .config/functional-script-revision.txt -
a check written for the pre-fallback world where the two could never
diverge. Once the fallback finally fired, prepare produced testing_sha
21edcf4 while the pin file still holds 27e9584 and every lane aborted
before checking out the test scripts.
Drop the pin-file comparison and keep what the lane actually needs to
guarantee: testing_sha is a valid commit sha (current_chain), the lane
checked out exactly that sha (record: private_head == testing_sha, kept
as-is), and the health checker validates the same format instead of
re-reading the pin file. Tests updated: a fallback testing_sha that
differs from the pin is accepted; a non-sha testing_sha is rejected.
Verified: python3 -m unittest test_functional_chain
test_functional_chain_health -> 39 tests OK.
hector