typo3 git problem

Fatal error: Uncaught exception 'LogicException' with message
 'No class loading information found for TYPO3 CMS.
  Please make sure you installed TYPO3 with composer
  or the typo3/contrib/vendor folder is present.'
in typo3_src-git/typo3/sysext/core/Classes/Core/Bootstrap.php on line 233