When I try to edit a page that has a forward slash in the URL, I get "Error:
bad page name". I think the problem is because the forward slash is escaped as
`%252F` instead of `%2F`.

For example, if I go to `http://ciffer.net/~svend/tech/hosts/` and click Edit,
I am sent to a page with the URL
`http://ciffer.net/~svend/ikiwiki.cgi?page=tech%252Fhosts&do=edit`.

I am running ikiwiki 3.20100504~bpo50+1 on Debian Lenny.