def prep_siderepo(self, workdir, packages, arch):
""" prepare a side repository given extra packages """
arch = [arch]
arch.append('noarch')
repodir = '{0:s}/siderepo'.format(workdir)
repo_create = RepoCreate(repodir, arch)
repo_create.make_repo(packages)
repo_url = 'file://{0:s}'.format(repodir)
return repo_url