Peer verification needs to be serial...

electrumx/server/peers.py

@@ -290,15 +290,10 @@ class PeerManager(object):
         peer.features['server_version'] = server_version
         ptuple = protocol_tuple(protocol_version)
 
-        # Do the rest concurrently
-        async with TaskGroup() as group:
-            await group.spawn(self._send_headers_subscribe(session, peer,
-                                                           ptuple))
-            await group.spawn(self._send_server_features(session, peer))
-            await group.spawn(self._send_peers_subscribe(session, peer))
-            # If any task errors out; bail
-            async for task in group:
-                task.result()
+        # FIXME: Make concurrent preserving the exception
+        await self._send_headers_subscribe(session, peer, ptuple)
+        await self._send_server_features(session, peer)
+        await self._send_peers_subscribe(session, peer)
 
     async def _send_headers_subscribe(self, session, peer, ptuple):
         message = 'blockchain.headers.subscribe'