Task #40095: Move core to namespaces
Fix test dependency to autoloader
The new class_alias() mapping in the autoloader makes the autoloader behave weird if it is unregistered and registered multiple times during one call. This is the case in unit tests and can lead to fatals in other tests. For now, the it is checked if the autoloader already loaded the class alias map to no redo this again and the internal mapping is not overwritten to an empty array.