Fix websocket initialization bug (#1389)
Fix websocket initialization bug (#1389)

This fixes a bug with the initialization path of the websocket patch code, which caused the recent failure on Cloud Shell and rollback.
craigcitro/datalab,googledatalab/datalab,parthea/datalab,parthea/datalab,craigcitro/datalab,parthea/datalab,yebrahim/datalab,yebrahim/datalab,googledatalab/datalab,yebrahim/datalab,craigcitro/datalab,googledatalab/datalab,parthea/datalab,craigcitro/datalab,googledatalab/datalab,yebrahim/datalab,parthea/datalab,yebrahim/datalab,parthea/datalab,craigcitro/datalab,googledatalab/datalab,googledatalab/datalab