Remove obsolete comment.

Lib/email/message.py

@@ -242,7 +242,7 @@ class Message:
             raise TypeError('Expected list, got %s' % type(self._payload))
         payload = self._payload
         cte = self.get('content-transfer-encoding', '').lower()
-        # payload can be bytes here, (I wonder if that is actually a bug?)
+        # payload may be bytes here.
         if isinstance(payload, str):
             if _has_surrogates(payload):
                 bpayload = payload.encode('ascii', 'surrogateescape')