Use the composer.json example on windows. In Addition to the composer manifest we provide a LocalConfiguration.php and AdditionalConfiguration with our provisioning. So the bootstrap is not in FIRST_INSTALL mode, maybe that's something that does have an influence? When we hit typo3/install to run DB compare to seed the database we do get:
Fatal error: Uncaught exception 'LogicException' with message 'No class loading information found for TYPO3 CMS. Please make sure you installed TYPO3 with composer or the typo3/contrib/vendor folder is present.' in ....
Note to self:
- check wether dropping provisionde typo3conf/* items and adding FIRST_INSTALL does make a change