'Changes to the stage directory and attempt to expand the downloaded
archive.  Fail if the stage is not set up or if the archive is not yet
downloaded.'

def expand_archive(self):

    archive_dir = self.source_path
    if (not archive_dir):
        self.fetcher.expand()
        tty.msg(('Created    stage    in    %s' % self.path))
    else:
        tty.msg(('Already    staged    %s    in    %s' % (self.name, self.path)))
