Wikimedia Bugzilla is closed!

the function tries to make a connection and check if this was successfull. If
not, it reports an error using "wfDebug".
So far ok.
Problem: even if connection wasn't successfull it will triy to send "SET NAMES
utf8" to the server, which throws an exception.

Solution: only send if connection successfull, in other case it makes no sens...

if ( !$success ) {
  $this->reportConnectionError();
} else {
  global $wgDBmysql5;
  if( $wgDBmysql5 ) {
    // Tell the server we're communicating with it in UTF-8.
    // This may engage various charset conversions.
    $this->query( 'SET NAMES utf8' );
  }
}

Result: Installation successfull!