T113839 is a failure of mwext-testextension-zend job on the Disambiguator extension about some issue with Metrolook. skins/Metrolook is not a dependency, but the repository was still around from a previous run.
For extensions, there is an extension_load.txt file, so we can keep the extensions between runs, but for skins there is no such things and I guess the skins are autoloaded.
So we need the job to clean up the skin dir.