PATH_site not defined in typo3/thumbs.php
We have used an include like this in one of the classes of an extension
This class was included inside the temporary config-cache files too. In general it worked fine but for the thumbs.php. During thumbnail generation the config-cache is loaded to. It failed because of the missng PATH_tslib constant.
I think it does no harm to define this constant inside thumbs.php even if it isn't needed there. It avoids such problems like ours.
(issue imported from #M15259)