The Worker.get_thread_id() method raises an error when the thread id is None, for example if the thread has not been started yet:
2018-12-21 10:10:25 12104 9736 ERROR nxdrive.engine.processor Unknown error Traceback (most recent call last): File "nxdrive\engine\processor.py", line 272, in _execute File "nxdrive\engine\processor.py", line 1143, in _synchronize_remotely_created File "nxdrive\engine\processor.py", line 1214, in _create_remotely File "nxdrive\engine\processor.py", line 960, in _download_content File "nxdrive\client\remote_client.py", line 295, in stream_content File "nxdrive\client\remote_client.py", line 290, in stream_content File "nxdrive\client\remote_client.py", line 175, in download File "lib\site-packages\nuxeo\operations.py", line 303, in save_to_file File "nxdrive\engine\engine.py", line 847, in suspend_client File "nxdrive\engine\workers.py", line 99, in get_thread_id RuntimeError: Unable to retrieve thread id
We should just let it slide.