TYPO3 Core

When I save the dataset form in the backend, it always ends with an error message:

Fatal error: Cannot use string offset as an array in /var/www/html/typo3cvs/TYPO3core/t3lib/class.t3lib_tcemain.php on line 1939:

if (is_array($dsConf['TCEforms']['config']) && is_array($dataValues[$key])) {

This happens only with PHP 5 and comes because $dsConf is empty.

(issue imported from #M2141)