Possible state inconsistency between `Notifications` and `ProtocolController` when incoming connection is dropped

[dmitry-markin]

There is a comment in Notifications behavior while handling ConnectionClosed event:

substrate/client/network/src/protocol/notifications/behaviour.rs

Lines 1238 to 1239 in 79d37ef

	// In the incoming state, we don't report "Dropped". Instead we will
	// just ignore the corresponding Accept/Reject.

This is likely incorrect behavior, because if we had already sent an "incoming" request to ProtocolController (aka "peerset") and it answered with "accept", it would be thinking that we are connected to this peer, while in reality the connection was dropped.

[dmitry-markin]

Looking into it more carefully, I see the implementation is actually correct. Just the comment should be updated to something like

 // In the incoming state, we don't report "Dropped" straight away. Instead we will 
 // report "Dropped" while handling the corresponding Accept.