Thanks for the tips Anthony!
After I added the groups wiki_editor and wiki_author and put my
signon into those groups, the wiki started working (it appears I have
a bit more to learn about how the wiki works now that it's working), but
I thought I was administrator at the time and it didn't automatically
set up those groups.
I think a one-sentence additional comment in default.py should mention
these additonal requirements. (or refer to the documentation in the
manual).
(And yeah, the underscore in "auth_wiki()" was just a posting typo, of course)
Rufus