[TYPO3-core] TYPO3 6.2 alpha5 Government package broken

[Steffen Kamper]

Hi,

installing the government package from install wizard is broken.
The error is 

PHP Fatal error:  require_once(): Failed opening required '/xxx/typo3/sysext/cms/tslib/class.tslib_pibase.php' (include_path='/xxx/typo3/contrib/pear/:.:') in /xxx/typo3conf/ext/wt_spamshield/Classes/Extensions/class.tx_wtspamshield_extensions_abstract.php on line 25, referer: http://xxx/typo3/install/index.php?TYPO3_INSTALL[type]=database&mode=123&step=4

after copying old class.tslib_pibase.php to this path, installation was ok.