Disallow any concurrent voice connections

Author: dolfies

discord/abc.py

@@ -2963,7 +2963,7 @@ async def connect(
         connectable = _channel or self
         channel = await connectable._get_channel()
 
-        if state._get_voice_client(key_id):
+        if state._has_voice_client():
             raise ClientException('Already connected to a voice channel')
 
         voice: T = cls(state.client, channel)

discord/state.py

@@ -1273,6 +1273,9 @@ def _update_voice_state(
     def _voice_state_for(self, user_id: int) -> Optional[VoiceState]:
         return self._voice_states.get(user_id)
 
+    def _has_voice_client(self) -> bool:
+        return bool(self._voice_clients)
+
     def _get_voice_client(self, guild_id: Optional[int]) -> Optional[VoiceProtocol]:
         # The keys of self._voice_clients are ints
         return self._voice_clients.get(guild_id)  # type: ignore