TYPO3 Core

After installation of an extension the cache (at least system cache) is cleared. This clears the classAliasMap caches as well (those are stored in cache_classes). So any class alias which is used by the current installed extension and added in another dependency causes a fatal error.

This was tested with the introduction package ("old realurl) and realurl 1.12.8. The bootstrap_package adds the class alias for t3lib_div which can't be found after realurl was uninstalled and installed again.