Last modified: 2008-09-03 14:48:07 UTC
See for example http://de.wikinews.org/w/api.php?action=query&prop=info&titles=Hauptseite&format=yaml compared to http://de.wikinews.org/w/api.php?action=query&prop=info&titles=Hauptseite Both the namespace (ns) and the counter variable are numerical zero but in the yaml output the value is just empty.
Upon seeing this bug, my first instinct was that PHP's weak type system was to blame, and that someone had done $var == '' somewhere (which is true if $var is '0'). It turned out there was a == '' in the YAML formatter, but that didn't cause the bug. It was plain, old-fashioned, non-PHP-related stupidity in the form of if($value), which was probably intended to be false for null and empty strings, but is also false for 0 and '0'. Fixed in r40384.