Listeners for ModifyLanguagePackRemoteBaseUrlEvent never called
The registered EventListeners for the event ModifyLanguagePackRemoteBaseUrlEvent are never called. This affects self-registered listeners as well as the core provided listener TYPO3\CMS\Install\Compatibility\SlotReplacement::onLanguagePackProcessMirrorUrl.
In the LanguagePackService of ext:install I called the function getAllListenerDefinitions() from $this->eventDispatcher->listenerProvider to test it. This function does not return any entries. It seems that the Services.yaml is completely ignored here. In the backend under the module "Configuration" all EventListeners appear correctly.