From the spec:
Once peers are ready to exchange commitment signatures, they must remember
the details of the funding transaction to allow resuming the signatures
exchange if a disconnection happens.
Basically this means we add channels to the database before we've gotten
commitments for them; it's nice that there's now a state for commitments
recevied but we now save the channel prior to that.
This commit makes it possible to track the pre-commit-rcvd but not quite
open-init state.
ecb8d9d71f