This returns false positives as long as the wikiname is a substring of an existing username.  `wiki_user_query("Eli")` will return True despite there being no such user (see `curl 'wiki.lesswrong.com/api.php?action=query' -d 'list=allusers&aufrom=Eli'`.

Add a "format=xml" parameter to the API call and tighten the check.  If XML parsing is too much of a pain, at the very least check for `"name=\"%s\"" % wikiname.replace('_', ' ') in content`

Exception handling is also needed -- currently if the API call fails, users will be unable to view their user page.  If the call does fail, the status of 'unknown' needs to be preserved so that subsequent attempts will take place.