kafka.py: return key as str rather than list

ligo/scald/io/kafka.py

@@ -89,8 +89,8 @@ class Client(object):
         for msg in self._consumer.consume(num_messages=max_messages, timeout=timeout):
             if msg and not msg.error():
                 if msg.key():
-                    key = msg.key().decode("utf-8").split(".")
-                    msg_tags = set(key)
+                    key = msg.key().decode("utf-8")
+                    msg_tags = set(key.split("."))
                 else:
                     key = None
                     msg_tags = set()