TYPO3 Core

1. Download and install via get.typo3.org/8
2. Install TYPO3
3. Create a Test-Extension with following depends configuration:

• array( 'extbase' => '8.7.0', 'fluid' => '8.7.0', 'typo3' => '8.7.0', 'recycler' => '', 'dce' => '', 'mask' => '', 'realurl' => '', 'cs_seo' => '', ),

4. Download the current extension list in extension manager via get extensions (I have not update via the update button, only over initial switch to "get extension")
5. Install the test extension which download the extensions from depends array
6. Error throws (class not found in my case from dce extension)
7. Delete autoload folder in typo3conf
8. Try reinstall the test extension
9. It works

When I add in this case in ext_emconf.php the autoload configuration which is since 6.2 not needed (you find a conversation about this here https://github.com/FriendsOfTYPO3/extension_builder/issues/39#issuecomment-303324207), it works.