Fix extraction of tarball with non existant uid/gid

        for ti in self.getmembers():

            total_sz += ti.size

        return total_sz

    def chown(self, tarinfo, targetpath):

        '''

        Overide real chown method from tarfile which make crazy check about

        uid/gid before chowning. This leads to bug when a uid/gid doesn't

        exitsts on the running system

        This overide as a sexy side effect which allow badly create tarball

        (whithout --numeric-owner) to be extracted correctly

        '''

        if hasattr(os, "geteuid") and os.geteuid() == 0:

            # We have to be root to do so.

            try:

                if tarinfo.issym() and hasattr(os, "lchown"):

                    os.lchown(targetpath, tarinfo.uid, tarinfo.gid)

                else:

                    if sys.platform != "os2emx":

                        os.chown(targetpath, tarinfo.uid, tarinfo.gid)

            except EnvironmentError, e:

                raise ExtractError("could not change owner")