Will revise all permissions code eventually when adopting the
permissions.db system.

Some wikis (like frwiki), set their projects to localized forms of
the expected (so "wikipedia" becomes "wikipédia"). An additional
search by URL in _get_site_name_from_sitesdb() fixes this.

* Apparently bool(cookiejar) is False if the cookiejar doesn't
contain any cookies, even if it exists. Change `if cookiejar` to
`if cookiejar is not None` to get around this.