https://bugzilla.wikimedia.org/show_bug.cgi?id=55219
--- Comment #13 from Morten Wang warnckew@online.no --- data.api.Request does kwargs.pop(), so if it gets instantiated with a max_retries parameter it will use that value, otherwise it reads the config parameter.
In my case I found that I can just set pywikibot.config.max_retries instead of passing it as a parameter to Page.save(). Arguably nicer than passing a parameter around, which requires some way of handling a default value. Sorry about not figuring that out earlier.