[PATCH 4/6] test index-pack on packs with recoverable delta cycles

The previous commit added tests to show that index-pack correctly bails in unrecoverable situations. There are some situations where the data could be recovered, but it is not currently: 1. If we can break the cycle using an object from another pack via --fix-thin. 2. If we can break

[PATCH 4/6] test index-pack on packs with recoverable delta cycles

The previous commit added tests to show that index-pack correctly bails in unrecoverable situations. There are some situations where the data could be recovered, but it is not currently: 1. If we can break the cycle using an object from another pack via --fix-thin. 2. If we can break