TYPO3 Core

This is due to the fact, that TYPO3 tries to resolve the path to the entry script in cli mode
by evaluating $_ENV['_'] first, then if this ist not set, $_SERVER['_'] is taken.

On systems where $_ENV['_'] isn't populated, this works, as the frontend test bootstrap populates $_SERVER['_'] with the correct value.
However there are some systems, where $_ENV['_'] is populated with the path to the PHP binary. In that case it fails
with the error message that TYPO3 is unable to determine path to entry script.

The main culprit though is, that in this scenario TYPO3 tries to determine paths based on a cli environment, while
in fact we emulate a frontend (HTTP server) environment.