The prune selected its targets with `abi_cache_risky_packages()`, the source
classifier. A dry run on ubuntu-2404-amd64 reports what that costs:
Dry run: 3013 object(s) left in place.
The classifier calls 93% of compiled packages risky; the binaries' own symbols
say 4.3%. Applying it would have deleted roughly 3000 working flat objects to
fix about 230 broken ones, turning every one of them into a source fallback for
clients that cannot be routed.
Select from `abi_flat_safety` instead, matching the object rather than the
package name: a package can have a safe flat binary at one version and an
unsafe one at another, and deleting both throws away a working binary. This is
the same correction #129 made to the index writer; the prune was written before
the verdicts existed and never followed.
The refusal guard moves with it. An empty result now means the slot's
flat-safety backfill never ran, which is exactly the state rhel8 was found in,
and pruning nothing while reporting success would have hidden it.
pat-s
68c3b6e66e