Add rollback strategy to Client.join_voice_channel

discord/client.py

@@ -3181,8 +3181,13 @@ class Client:
 
         # request joining
         yield from self.ws.voice_state(server.id, channel.id)
-        session_id_data = yield from asyncio.wait_for(session_id_future, timeout=10.0, loop=self.loop)
-        data = yield from asyncio.wait_for(voice_data_future, timeout=10.0, loop=self.loop)
+
+        try:
+            session_id_data = yield from asyncio.wait_for(session_id_future, timeout=10.0, loop=self.loop)
+            data = yield from asyncio.wait_for(voice_data_future, timeout=10.0, loop=self.loop)
+        except asyncio.TimeoutError:
+            yield from self.ws.voice_state(server.id, None, self_mute=True)
+            return None
 
         kwargs = {
             'user': self.user,