bundle2: call a hook after the transaction is closed We call a dedicated hook right after closing the transaction. This will let people react to the transaction with all the information in hand. This hook is experimental and will not survive in future versions.

bundle2: call a hook prior to closing the transaction We call a dedicated hook right before closing the transaction. This will let people abort unbundling with all the information in hand. This hook is experimental and will not survive in future versions.

bundle2: inform transaction that we are in a bundle2 unbundle That way, hooks called during the unbundle process are aware that a bigger picture is going on.

changegroup: use tr.hookargs when calling changegroup hooks So that other parties using the transaction can put information in our hook calls.