Description
@valentinewallace pointed out that our current API doesn't do anything to remember wallet birthdays. If a user initializes a ChannelManager, then opens a channel, then shuts down before ever seeing a block (which is reasonable on first-startup), they may restart later and deserialize and think they don't need to connect any blocks at all, missing the funding transaction confirmation. Further, ChannelMonitors could exhibit similar behavior, potentially even missing more if users don't persist them without updates.
One potential fix for this would be to (a) require a birthday current-tip block hash when constructing a ChannelManager and then (b) copy the current block hash into ChannelMontiors when constructing them. This would effectively imply reverting #819, though it didn't actually introduce this issue, only surfaced it.