Debug log if check_version connection attempt fails

Author: dpkp

kafka/client_async.py

@@ -1052,6 +1052,8 @@ def check_version(self, node_id=None, timeout=None, **kwargs):
 
                 if conn._api_version is not None:
                     return conn._api_version
+                else:
+                    log.debug('Failed to identify api_version after connection attempt to %s', conn)
 
             # Timeout
             else: