Yes, that makes even the capitalized "CON" issues go away. It's not a
one-to-one mapping, though ("foo-" and "foo_" map to the same entity).

foo_ would map to foo__, and foo- would map to something else.
(foo- as we do not rewrite dashes, yet?)

If we want that, too, I think something like url-encoding is fine, with
the caveat that we simply urlencode _more_ things (i.e., anything not in
[a-z_]).

Yeah I think we need more than url encoding now.