Wikimedia Bugzilla is closed!

CURL command:
============================
curl --silent --include \
 -F 'url'='x' \
 -F 'blog_name'=\
 -F 'article'='\</H2>'\
 -F 'title'='Main Page'\
 -F 'excerpt'='BLAH'\
 'localhost/wiki/trackback.php'
============================

LocalSettings.php includes this: 
============================
$wgUseTrackbacks = true;
error_reporting (E_ALL);
============================
(i.e. stricter error reporting, and trackbacks usage enabled).

Resulting HTML output is:
============================
<br />
<b>Fatal error</b>:  Call to a member function exists() on a non-object in
<b>/var/www/hosts/mediawiki/phase3/trackback.php</b> on line <b>53</b><br />
============================