PHPOffice/PHPExcel — pull request #350 by Restless-ET (2014-04-09 15:53:33+00:00)
Title: Keep/set the value on _loadSheetsOnly as NULL ...

... when calling setLoadSheetsOnly() with NULL as argument (the default value) so that all worksheets are loaded, otherwise we'll end up getting an empty array, which means that no worksheet is loaded at all.