The post-sync hooks run even when the sync fails

[Ævar Arnfjörð Bjarmason]

See issue #15 for the larger problem here. Arguably we should have hooks that run pre/post phase no matter what, but once we have the sequencer discussed in issue #15 this should become a non-issue mostly.

[Fernando Vezzosi]

We could give the hooks a way of telling the outcome/success of each (already-run) step, and then each hook would have the information needed to decide on how to act appropriately.