I checked a name and got the IPs it was using. So far so good. Then I tried
checking the IPs to see what names were using them, and reliably got:
Fatal error: Call to undefined function: recentchangesline() in
/usr/local/apache/common-local/php-1.5/extensions/CheckUser.php on line 93
This happens with any IP, whether entered by hand or looking from a CheckUser
page generated by a username query.
Version: unspecified
Severity: normal
URL: http://en.wikipedia.org/wiki/Special:CheckUser