remove channel from channel_timestamps if funding_tx has been dropped from mempool

electrum/lnwatcher.py

@@ -336,6 +336,7 @@ class LNWalletWatcher(LNWatcher):
         if not chan:
             return
         if funding_height.height == TX_HEIGHT_LOCAL:
+            self.lnworker.channel_timestamps.pop(bh2u(chan.channel_id))
             return
         elif closing_height.height == TX_HEIGHT_LOCAL:
             await self.lnworker.update_open_channel(chan, funding_txid, funding_height)