Subfolder requires identifier when parent folder is expanded.

Resolves: #80166
Releases: master, 7.6
Change-Id: I5226f425951f9124dcaa3e9780b52354e266382d
Reviewed-on: https://review.typo3.org/51974


Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>