Same mistake as the source-fallback share. The packages a non-primary
minor lacks are ABI-risky ones built under the slot's primary minor,
which a client on another minor cannot safely load: their absence is
correct, not a defect. Failing on it blocked resolute and alpine324 on
both arches while they regressed nobody.
Parity gates the claim we make about coverage; MAX_REGRESSIONS gates
whether routing is safe to enable. Only the second belongs in the exit
code.
pat-s
ed131e19fa