Fixed in the next release. This occurred only when the Wiki File Name was set to a blank value. Note that by fixing this, failed wiki routes will NEVER pass to the default script if the filename is blank, as it will always say that an article by that name does not exist. Thus, other rewrites must be set explicitly in .htaccess, or the wiki should only be used on a unique sub-domain, or the wiki base URL should at least point to a different location than the rest of the forum when the filename is set to a blank value.