detect conflicting channel backups, add warning before channel creation

electrum/lnrater.py

@@ -243,9 +243,6 @@ class LNRater(Logger):
         node_keys = list(self._node_stats.keys())
         node_ratings = list(self._node_ratings.values())
         channel_peers = self.lnworker.channel_peers()
-        channel_backup_peers = [
-            cb.node_id for cb in self.lnworker.channel_backups.values()
-            if (not cb.is_closed() and cb.get_local_pubkey() == self.lnworker.node_keypair.pubkey)]
         node_info: Optional["NodeInfo"] = None
 
         while True:
@@ -264,7 +261,7 @@ class LNRater(Logger):
             if pk in channel_peers:
                 continue
             # don't want to connect to nodes we already have a channel with on another device
-            if any(pk.startswith(cb_peer_nodeid) for cb_peer_nodeid in channel_backup_peers):
+            if self.lnworker.has_conflicting_backup_with(pk):
                 continue
             break