chainntnfs: skip conf dispatch if ntfn already dispatched

This mirrors the logic for the spend case. This prevents a double
dispatch scenario when combined with a later commit. Otherwise, the
confirmation would linger in the buffer which is not ideal.

chainntnfs/txnotifier.go

@@ -872,10 +872,13 @@ func (n *TxNotifier) UpdateConfDetails(confRequest ConfRequest,
 func (n *TxNotifier) dispatchConfDetails(
 	ntfn *ConfNtfn, details *TxConfirmation) error {
 
-	// If no details are provided, return early as we can't dispatch.
-	if details == nil {
-		Log.Debugf("Unable to dispatch %v, no details provided",
-			ntfn.ConfRequest)
+	// If there are no conf details to dispatch or if the notification has
+	// already been dispatched, then we can skip dispatching to this
+	// client.
+	if details == nil || ntfn.dispatched {
+		Log.Debugf("Skipping dispatch of conf details(%v) for "+
+			"request %v, dispatched=%v", details, ntfn.ConfRequest,
+			ntfn.dispatched)
 
 		return nil
 	}