The new Makefile-based command ``make serve-selenium-notebooks`` will serve notebooks in lib/galaxy_test/selenium/jupyter.
The notebooks will target a Galaxy host running on port 8080 - but are parameterized to be run with papermill (https://papermill.readthedocs.io/) for automate targeting different Galaxy servers, remote Selenium servers, etc..
Screenshots will be embedded right into the notebook.
Example notebooks setup to target just the library code in ``galaxy-selenium`` as well as one appropriate to leverage the Galaxy testing framework are included and documented in depth via modules docstring for ``galaxy_test.selenium.jupyter``.
Upgrade syntax using `pyupgrade --py36-plus` .
Manually drop several `six` imports.
Also:
- Remove broken pr_cache in scripts/bootstrap_history.py
- Fix broken prefix removal in lib/galaxy/tool_util/deps/mulled/mulled_build.py
John Chilton