Comment (by Roland Haas):

@Bill Gabella I think I see what you mean. In my case though, the tab icon does eventually switch back from the hourglass to the regular notebook icon. On the other hand I am left with some cells still showing the "*" busy marking even after everything finished running. We seem to not be the only ones affected: https://github.com/jupyter/notebook/issues/2748 and I verified that our jupyter code does indeed not have the lines proposed as a fix. I will verify if the proposed fix works for us and if so propose a change to the docker file to patch jupyter in the container.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2234/trouble-in-the-tutorial-server