Problem with ServiceContext in ServiceContextManager

After a longer period I updated my tamaya sources from master and deployed them into my existing karaf project. After that the core tamaya-core bundle fails to start the OSGIActivator because of ConfigException "No ServiceContext found".
The exception comes from ServiceContextManager::loadDefaultServiceProvider which always try to get a new(best) Service Provider instead of using the one got from ServiceContextManager::set method like in older implementations. The problem is that ServiceLoader.load(ServiceContext.class, classLoader) doesn't find anything and I ask myself if it shouldn't be a OSGIServiceLoader do find the service declaration.