In trunk I've enabled the Debug variables and the following line showed up among others:
0.0271 Class SkinVector not found; skipped loading
Originated from AutoLoader.php
static function autoload( $className ) {
...
if ( !$filename ) { if ( function_exists( 'wfDebug' ) ) { wfDebug( "Class {$className} not found; skipped loading\n" ); }
..
}
Version: 1.18.x
Severity: minor