Merge branch 'tb/pack-with-duplicates' into seen

The handling of packfiles with duplicate object entries has been hardened. Specifically, reverse index lookup, delta cycle recovery, multi-pack-index verification, and pack reuse paths have been updated to correctly handle or gracefully reject duplicate entries. * tb/pack-with-duplicates: pack-bitmap: handle duplicate pack entries during MIDX reuse test-tool bitmap: reject packs with duplicate objects midx: verify duplicate pack entries by OID and offset packfile: recover delta cycles through duplicate entries t5308: test reverse indexes with duplicate objects