ln: fix race in on_network_update

electrum/lnworker.py

@@ -114,6 +114,11 @@ class LNWorker(PrintError):
         self.network.trigger_callback('channel', chan)
 
     def on_network_update(self, event, *args):
+        """ called from network thread """
+        # Race discovered in save_channel (assertion failing):
+        # since short_channel_id could be changed while saving.
+        # Mitigated by posting to loop:
+        async def network_jobs():
             for chan in self.channels.values():
                 if chan.state == "OPENING":
                     res = self.save_short_chan_id(chan)
@@ -129,6 +134,7 @@ class LNWorker(PrintError):
                     conf = self.wallet.get_tx_height(chan.funding_outpoint.txid)[1]
                     peer = self.peers[chan.node_id]
                     peer.on_network_update(chan, conf)
+        asyncio.run_coroutine_threadsafe(network_jobs(), self.network.asyncio_loop).result()
 
     async def _open_channel_coroutine(self, node_id, local_amount_sat, push_sat, password):
         peer = self.peers[node_id]